CHEMICAL 


ittKntfA  '.->w 

UBKAW 

UMIVetSITY  OF 


CHEMICAL  PRIMER: 


AN  ELEMENTARY  WORK 


FOR    USE    IN 


HIGH  SCHOOLS,  ACADEMIES,  AND 
MEDICAL  COLLEGES. 


BY 


S.  P.  MEADS, 


FOURTH    EDITION. 

THIRTEENTH  THOUSAND. 


W.  B.   HARDY,  PUBLISHER, 
961    BROADWAY, 

OAKLAND,    CAL. 
1685. 


ENTERED  ACCORDING  TO  ACT  OF  CONGRESS  IN  THE  YEAR  1885, 

BY  S.  P.  MEADS, 
IN  THE  OFFICE  OF  THE  LIBRARIAN  OF  CONGRESS,  AT  WASHINGTON,  D.  C. 


PACIFIC     PRESS, 

[f  pilfers,  •  Eleclr><z>f^rper>s,  •  ^  •  J^irjeUrs, 
OAKLAND,  CAL. 


Add  '} 
GIFT 


.  Lib 


Preface  to  Second  Edition. 


Primer  has  been  prepared  for  use  especially  in  those  schools 
*na*  can  £iye  *°  chemistry  only  one  term's  work.  It  has  grown 
out  of  the  needs  of  the  class-room,  as  I  have  felt  them.  Its 
statements  are  necessarily  somewhat  narrow,  confining  the  pupil  to  gen- 
eral rules.  Refined  accuracy  means  a  treatise,  not  a  primer.  I  have 
given  in  the  following  pages  as  much  as  I  think  the  average  class  can 
digest  in  a  single  term,  and  I  hope  my  fellow- teachers  will  carefully 
examine  the  plan  throughout  before  passing  judgment. 

I  have  freely  consulted  whatever  chemical  works  were  within  my 
reach,  especially  Attfield,  Barker,  Roscoe  and  Schorlemmer,  Eliot  and 
Storer,  Appleton,  and  Jones. 

For  criticisms  and  valuable  suggestions  in  preparing  this  Second  Edi- 
tion, I  am  indebted  to  Prof.  Joseph  LeConte  and  Prof.  W.  B.  Rising, 
of  the  University  of  California.  I  wish  to  acknowledge  my  obligation 
to  many  teachers  who  are  using  my  humble  work  in  their  classes,  es- 
pecially to  Prof.  Geo.  R.  Kleeberger,  of  the  State  Normal  School,  San 
Jose,  and  to  Mr.  Volney  Rattan,  of  the  Girls'  High  School,  San  Fran- 
cisco. Nor  should  I  forget  my  indebtedness  to  Mr.  C.  B.  Bradley  in 
the  preparation  of  my  First  Edition. 

An  experience  of  three  years  in  teaching  chemistry  to  medical  stu- 
dents has  enabled  me,  I  hope,  to  anticipate  their  wants  in  several  direc- 
tions. It  has  shown  me  how  greatly  they  need  an  elementary  book 
before  opening  the  excellent  but  voluminous  works  which  should  be 
their  life  companions. 

Natural  Science  Dept.,  S.  P.  MEADS. 

Oakland  High  School,  Jan.  2,  1884. 


Preface  to  Fourth  Edition. 


HE  unexpected  exhaustion  of  the  Second  Edition  of  this  work  in 
the  space  of  six  months,  for  use  in  the  schools  of  California  alone, 
made  it  necessary  for  me,  in  order  to  meet  the  demand,  to  send 
the  Third  Edition  hastily  to  press.  I  have  taken  the  opportunity  to 
make  a  few  more  corrections  in  the  plates  before  printing  this  Fourth 
Edition.  I  wish  to  express  my  hearty  thanks  to  my  fellow-teachers 
for  their  kindly  appreciation  of  my  efforts  to  present  plainly  and  tangi- 
bly to  beginners,  the  A,  B,  C  of  chemistry.  I  thank  them  no  less  sin- 
cerely for  valuable  criticisms. 

Oakland,  California,  S.  P.  MEADS. 

Jan.  2,  1885. 


937 


BRIEF  SUGGESTIONS-MIXED. 


DO  not  allow  pupils  lazily  to  pronounce  the  symbol  or  the  formula 
instead  of  the  name,  i.  e.,  wherever  "H"  occurs,  see  that  it  is 

called  hydrogen Have  the  pupils  copy  the  two  Reference  Tables 

(pp.  16,  29)  upon  cardboard,  and  allow  them  the  free  use  of  these  for 
the  entire  term.  Never  compel  them  to  memorize  formulas,  atomic 
weights,  strength,  etc.  It  is  as  important  to  know  what  not  to  remem- 
ber, as  to  know  what  should  be  remembered,  since  the  former  comprises 

by  far  the  larger  portion  of  any  text-book Let  the  pupils  perform 

all  experiments  (except,  perhaps,  a  few  difficult  ones,  or  for  the  sake 
of  taking  your  turn  with  the  class)  in  presence  of  the  class,  explaining 
each  experiment  as  it  proceeds.  It  takes  time,  but  it  is  the  only  way  to 
teach  chemistry  where  a  table  for  each  student  cannot  be  provided.  If 
you  haven't  time,  omit  half  the  experiments  to  accomplish  this  result. 
Assign  to  separate  pupils  one  experiment  each  a  few  days  beforehand. 
The  experiments  may  be  performed  upon  a  plank  table  (see  FRONTIS- 
PIECE), costing  not  over  four  dollars Every  experiment  teaches 

something,  and  the  sooner  you  can  impress  this  fact  the  better.  While 
you  should  make  every  experiment  as  impressive  as  it  can  be  made,  get 
the  pupils  through  the  babyhood  which  craves  noisy  or  showy  experi- 
ments, as  early  in  the  term  as  possible See  that  a  number  of  larger 

works  upon  chemistry  are  at  your  desk  for  reference After  you 

have  passed  the  "Reactions,"  encourage  any  pupils  who  may  show  a 
special  liking  for  the  science  to  work  out  after  school  hours  a  number  of 
solutions  (not  too  complex,  and  mixed  by  you)  by  the  Analytical  Charts. 

Teach  pupils  to  use  small  flasks  (test-tubes  answer  well)  and  small 

quantities  of  chemicals.  It  isn't  necessary  to  burn  a  forest  to  prove  that 
hydrocarbons  are  combustible,  nor  to  blow  up  a  continent  to  prove  a 

substance  explosive Do  not  be  afraid  to  teach  anything  contrary  to 

the  text,  if  you  have  good  authority  for  it;  but  let  disputed  points  alone. 
Teach  any  simple  principles  beyond  the  text,  instead  of  others  more 
complex  omitted;  but  do  not  teach  intricate  matter  outside  of  text,  else 
the  result  will  be  pupils  will  know  neither  the  text  nor  the  "intri- 
cate matter." Remember  that  one  of  the  chief  ends  of  a  small  text 

book  in  science  is  to  teach  the  pupil  to  read  intelligently  larger  works. 

Spend  at   least   half  the   time   in  reaching   carbon,   page  63. 

Use  the  METRIC  SYSTEM  throughout;   it  is  the  system Use 

either  thermometer.  The  CENTIGRADE  (C)  is  used  in  this  book,  though 
the  corresponding  Fahrenheit  (F)  degrees  are  given  in  a  few  places. 


INSERTED^  NOTES. 

PAGE  13. — That  which  is  called  "strength"  must  be  carefully  dis- 
tinguished later  in  the  course  from  chemical  affinity  (activity),  but  the 
distinction  had  better  not  be  made  till  the  superior  affinity  of  chlorine 
is  shown  by  Exps.  81  and  85. 

PAGE  19. — The  use  of  "ic"and  "ous"  as  adjectives  is  a  colloquial 
use  of  the  suffixes,  and  should  be  confined  to  the  class  room.  The  same 
might  be  said  of  a  few  other  expressions  used,  as  "pet  name,"  applied 
to  acids,  and  "  change  of  partners,"  applied  to  reactions. 

PAGE  37.  — In  addition  to  the  fact  that  water  favors  chemical  change, 
the  student  learned,  in  Chap.  IV,  that  electricity  also  may  produce 
chemical  change.  From  Exps.  1,  2,  3  and  4  he  learns  that  heat  favors 
chemical  change.  From  the  note  on  this  page  (page  37),  and  from  Exps. 
69  and  70,  he  adds  light  to  these  agents,  and  remembers  that  direct  sun- 
light is  shut  out  from  the  parlor,  that  the  carpet  may  not  fade.  In  or- 
ganic chemistry,  he  recognizes  a  fifth  active  influence  in  producing 
chemical  change,  viz. :  the  so-called  "  vital  force." 

PAGE  40. — Hydrogen  sulphide  keeps  longer  in  dark  bottle.  Compare 
Exps.  69  and  70  — An  arrow  indicates  an  escaping  gas. 

PAGE  41. — The  test-tube  stand,  in  Fig.  9,  represents  by  far  the  most 
convenient  form  for  ordinary  use.  [f  a  single  test-tube  is  placed  before 
the  class,  they  are  sure  then  to  be  looking  at  the  right  one,  which  is 
often  not  the  case  if  there  is  an  ordinary  rack  full  of  tubes. 

PAGE  44.— Fig.  10  represents  a  tin  dish  mounted  on  wooden  stand. 
There  are  two  round  openings  in  cover,  with  inserted  beakers,  and  orifice 
in  corner  of  cover  for  escaping  steam.  The  arrangement  did  good 
service  for  several  years  An  iron  basin,  with  cover  having  concentric 
rings  to  receive  evaporating  dishes  of  different  sizes,  is  more  convenient. 
A  coal  oil  stove  makes  a  cheap  source  of  heat  for  water-bath. 

PAGE  51.— Exp.  28.     (See  Note  3,  page  158.) 

PAGE  53. — For  cut  of  gasholder  see  Frontispiece  3.  Soft  rubber 
cork  should  be  used  in  it. 

I'.tGK  62. — Stop-cock  in  pipe  B  (cut)  is  closed  after  liquid  ammonia  is 
formed  in  1  >,  and  opened  after  generator  A  is  cooled. 

PAGE  71. — Strong  drafts  of  either  air  or  "fire-damp,"  are  dangerous, 
as  the  flame  is  liable  to  be  blown  through  the  gauze  of  the  ordinary 
I  >;ivy's  lamp  before  time  enough  elapses  to  cool  down  the  burning  gases. 

PAGE  73. — In  Exp.  67,  taper  must  be  lowered  very  steadily,  as  well  as 
promptly,  into  jar,  as  the  product  of  burning  (H  Cl)  is  a  non-sup- 
porter of  combustion. 

PAGE  75.  —  It  is  important  to  remember  how"  the  prominent  acids  are 
made.  (See  Exps.  75,  39  and  94,  with  Comments,  also  bottom  page 
140). — Deflagrates  is  technical  term  for  "burns  explosively."  Exp.  79. 

PAGE  78.— Question  No.  1.  Three  methods  of  making  oxygen  have 
been  shown  thus  far,  viz. :  one  in  Chap.  IV,  one  in  Exp.  2,  and  one  in 
Exp.  19.  Question  No.  2,  and  similar  ones,  ought  to  be  thoroughly 
mastered. 

PAGE  80. — Some  eggs  contain  an  excess  of  oil,  and  Exp.  88  is  unsuc- 
cessful because  of  it.  Boil  egg,  and  a  single  piece  of  white  placed  upon 
the  coin,  will  quickly  make  the  sulphide  evident. — lu  Exp.  89,  remove 
hair  after  boiling,  and  color  develops  with  time  and  becomes  darker. 

PAGES  90  and  91.— In  Exps.  109  and  111,  use  "  bleaching  powder " 
solution.  Pure  chloride  of  calcium  solution  dissolves  neither  arsenicum 
nor  antimony. 


PAGE  102. — Bessemer's  process  should  be  clearly  understood  in  its 
essentials,  viz.:  (1)  The  removal  of  all  the  carbon  by  the  great  heat ; 
and  (2)  putting  carbon  in  again  in  the  proportion  desired. 

PAGES  105  and  106. — Aluminum  is  now  made  much  more  cheaply  by  a 
new  process,  directly  from  corundum.  Pulverized  charcoal  is  packed  with 
corundum  in  furnace,  and  a  strong  electric  current  passed  through 
raises  the  charcoal  to  high  temperature,  and  the  greater  portion  of  the 
corundum  is  deoxidized,  leaving  the  fused  and  comparatively  pure 
metal.  This  process  will  probably  supersede  the  older  method  of 
reducing  the  chloride  by  sodium.  (See  sodium,  page  112.)  Alumi- 
num, if  cheap,  would  be  used  extensively.  As  its  tenacity  is  about 
nine-tenths  that  of  steel,  and  its  weight  only  about  one-third  that  of 
steel,  how  valuable  it  would  be  in  shipbuilding  is  evident.  If  "air 
ships  "  are  ever  to  be  of  practical  use  in  the  calm  belts  (doubtful)  Al 
will  be  the  needed  metal  to  harness  the  motive  power.  A  small  per- 
centage of  aluminum  increases  greatly  the  tensile  strength  of  brass  and 
other  alloys.  "Every  clay  bank  is  an  aluminum  mine."  This  wide 
distribution  of  the  metal  seems  to  mean  that  it  is  to  be  used  as  widely. 
It  is  by  far  the  most  abundant  metal. — Boron,  silicon,  and  other  ele- 
ments, may  be  deoxidized  by  above  process.  (Cowles  Bros.,  Cleveland, 
Ohio.) — Burnt  alum  is  nothing  but  alum  with  its  water  of  crystalliza- 
tion driven  off.  (See  Exp.  34.) 

PAGE  1 1 3.  — Leblanc's  process  should  be  thoroughly  understood.  The 
process  gives  us  cheap  sodium  carbonate  and  consequently  cheap  soap 
and  cheap  glass,  two  articles  very  necessary  to  the  health  of  a  people. 
It  also  gives  us  a  cheap  method  of  softening  hard  water.  (See  page  129. ) 

PAGE  118. — In  connection  with  the  thorough  mastering  of  the  plain 
facts  of  the  two  fermentations,  the  third,  destructive  fermentation, 
(page  121),  by  which  the  vinegar  returns  to  the  mineral  kingdom,  should 
be  noticed. 

PAGE  122.— In  Exp.  134  use  hard  bone,  free  from  marrow  and  the  fat 
which  is  found  in  the  bone  near  the  joints.  This  secures  the  best  results. 

PAGE  125. — The  remarks  under  Theory  of  Types  is  intended  to  cor- 
rect certain  false  impressions,  necessarily  imbibed  from  the  methods  of 
"putting  things"  iu  an  elementary  work.  Let  the  bright  pupil  read 
them  carefully. 

PAGE  128.— To  obtain  soap  (Exp.  137)  free  from  oil,  boiling  must  be 
continued  longer  and  a  slight  excess  of  the  alkali  used. 

PAGE  138. — Special  attention  should  be  called  to  statement  No.  5. 


The  following  typographical  corrections  will  be  made  in  the  Fifth 

Edition: 

Page  33,  Exp.  1.— "Fillings"  will  be  "tilings." 

Page  114. — "Ammonia  hydrate"  will  be  "Ammonium   hydrate." 

Page  13(5,  second  line.— "(KCN)"  will  be  "(HCN)." 

Pages  90  and  1)1. ,  Exps.  109  and    111.— "Calcium  chloride  solution" 

will  be  "bleaching  powder  solution,"  as  referred  to  above. 


The  above  "Notes"  have  been  inserted  to  make  the  book  as  valuable 
as  possible  in  the  class  room,  regardless  of  the  lack  of  policy  in  calling- 
attention  to  minute  mistakes  or  omissions  in  an  edition  upon  the  market. 
Criticisms  from  teachers  will  be  thankfully  received  and  carefully 
considered.  S.  P.  M. 

Oakland,  Cal,  June,  188G. 


INDKX. 


PAGE.    I  PAGE. 

ACID,  ACETIC 121,  132  ;  Ammonium 61,  62,  114 

' '      Benzole 133  ,  Ammonia 60,  61 ,  62 


Boracic 85 

Carbolic 121,  137 

Carbonic 66,  159 

Citric 124 

Gallic 124 

Hydrochloric 75 


Lactic 160 

Malic 124 

Muriatic 75 

Nitric 59,  60 

Oleic 16,  130 

Oxalic..,  ..124 


Type 125,  126 

Anaesthetic 59,  120,  121 

Analytical  Charts 162,  163 

Aniline 126,  147 

Antidotes 133 

Antimony 91,  152 

Antiseptic.  ..  .81,  97,  111,  112,  121 

Aqua-fortis 60 

Aqua-regia 60,  75,  152 

Arsenicum 88,  135,  152 

Atomic  Theory .10,  etc. 


Atmosphere 34,  47,  58,  67 

Palmitic 16  Atoms 10713,  etc. 

Picric 147  Atropia 127,  158 

Prussic 58,  7! 

BALSAMS...  ..133 


Salts 140 


Stearic.  . 


.  .  16,  130 


Sulphuric 81 


Tannic. 


124,  12.3 


"      Tartaric 124 

Acids ..25,  135 

Aconite 127,  136,  158 


Air. 


.34,47,  58,  67 


Albumen 122,  134,  156 

Alcohol 119,  120 

Alkalies 25,136 

Alkaloids 125,  127,  136,  157 

Alloys 91,143 

Alum 148,  154 

Aluminum   105,  106,  154 

Amalgam   91 


Barium 109,  155 

Bases 25,  136 

Basic  Salts 141 

Beer 119 

Belladonna 127,  158 

Benzol 70,  121 

Bessemer's  Process 102 

Binary  Compounds 11,  17 

Bismuth 104 

Bleaching 74,  81 

Powder 74 

Blowpipe 53,  71,  94,  162 

Borax 85 

Boron . .  85 


Brass. 


143 


Amber 


133  j  Bread-making 122 


INDEX, 


PAGE. 

Brimstone See  Sulphur. 

Bromine 76 

Bronze 143 

Bunsen's  Burner 70 

CALCIUM 107 

"  Light 108,  154 

Calomel 97 

Camphor 133 

Candles 69,  130 

Caoutchouc  133 

Carat 93 

Caramel 117 

Carbon 63 

Carbon  Dioxide 66,  159 

Carmine .  • 148 

Cast-iron 101 

Cellulose 116 

Chalk 108,  135 

Charcoal 63 

Chemistry  of  Candle 69 

"  Cooking 122 

"  "  Cleaning 131 

Chlorine 72,  150 

Chloroform 120 

Chloral 121 

"  Hydrate 121 

Choke-damp 68 

Chromium 92 

Cinnabar 96 

Clay 87,  106 

Coal  Gas 70 

Cobalt 104 

Cochineal 148 

Coin 143 

Coke 63,  70 

Collodion 116 

Compound  Ethers 120 

"  Radical 18 

Combustion 34,  48,  49 

Copper 100,  134,  154 


Corrosive  Sublimate 97 

Cotton 116 

Cream  of  Tartar 124 

Creosote 121 

Crystallization 50,  145,  146 

Cupellation 95 

Cyanogen 78 

DAVY'S  SAFETY  LAMP 71 

Deliquesence 56 

Dextrin 116 

Dextrose    117 

Dialysis 158 

Diamond 63 

Diastase 118 

Diffusion  of  Gases 52,  58 

Disinfectant 50,  64,  73,  121 

Distillation 57,  119,  120 

Dyeing 147 

EFFLORESENCE 56 

Elements 16 

Essences 120,  132 

Etchings 60,  77 

Ether 120 

Ethyl  Hydrate 119 

"      Oxide 120 

FATS 128 

Fermentation 118,  130 

Fireworks Ill,  155 

Flame 69 

Fluorine 77 

Formula,  Empirical 115 

"         Rational 115 

Fusil  Oil 120 

Fusible  Metal 104 

GALENA 98 

Galvanized  Iron 103 

Gas,  Illuminating 70 

Gelatin 122,  125 

German  Silver  . .  .  .  143 


INDEX. 


Glass 86,  87  I 

Glue 122  | 

Gluten 122 

Glycerin 130 

Gold 92,  153 

Graphite 63 

Gum  Arabic 116 

Gum  Resin 133 

Gun  Cotton 116 

Gunpowder Ill 

Gutta-percha 133 

Gypsum 108 

HALOGENS 27,  72 

Hard  Solder 143 

"     Water 54 

Hematite 23,  101 

Hydrocarbons 48 

Hydrogen. 50,  149 

Hydrogen  Sulphide 82,  162 

INDIA-RUBBER 133 

Indigo 147 

Ink 73,  125,  132 

"  Printers' 73 

Iodine 76 

Iron 101 

Isomerism 115 

LAKE 148 

Laudanum 127,  130 

Laughing-gas    59 

Lead 98,  103 

Leather 125 

Lime 107 

Lime-light 154 

Linen 116 

Litmus 25 

Litharge 65  j 

Logwood 148  I 

Lunar  Caustic 95  j 

Lye 129,  1361 


PAGE. 

MADDER 148 

Magnesium 34,  106 

Malt 119 

Manganese 105 

Marble 108 

Marsh-gas 70 

Matches 83 

Mercury 96,  153 

Metals 92 

Methyl  Alcohol 120 

Metric  System 160 

Milk 122,134 

Miscellaneous  Questions,  45, 78, 138 

Molasses 117 

Mordant 148 

Morphine. 127,  136,  157 

Mortar 108 

XAPTHA 110,  112 

Nascent  State 63 

Nickel 104 

Nicotine 127 

Nitre Ill 

Nitrous  Oxide 59 

Nitrogen 57 

Nomenclature 17,  24 

OILS 128 

Olein 128 

Opium 127,  136,  157 

Organic  Acids 124 

"       Bases 127,  157 

"       Chemistry 114 

Oxides 34 

Oxygen 46,  149 

Ozone 50 

PAPER 116 

Paregoric 127 

Pearlash Ill 

Pencils 63 

Petrifaction 86 

Pewter . .  . .  143 


8 


INDEX. 


Phosphoresence 84 

Phosphorus  ..    ..83,  137,  151,  152 

Photography 95,  96,  153 

Plants,  Office  of 67 

Plaster  of  Paris 108 

Platinum 94,  149 

Plumbago 63 

Porcelain 87 

Potash ..110 

Potassium 110 

QUARTZ 86,93 

Quicksilver 96 

Quinine 127,  157 

REACTIONS 33 

Reference  Table  1 16 

Table  II 29 

"          Table  IL— (con.)...  160 

Resin 133 

iiochelle  Salt 141 

Rosin 133 

SAGO 116 

Sal-ammoniac 60,  114 

Saleratus Ill 

Salt,  Common 112 

Salts 25 

Salts,  acid,  etc 140 

Salts,  Epsom    106,  135 

Salts,  Glauber's 113 

Salts,  Rochelle 141 

Saltpetre Ill 

Sand .  .  86 

Selen-salts 142 

Shellac 133,  155,  158 

Shot 143 

Silicon 85 

Silver 94,  153 

Soap ...128,131 

Sodium 112 

Solder 143 


Solution 37 

Spectrum  Analysis 143,  144 

Stalactites 108 

Starch 115,  122 

Stearin 128 

Steel 102 

Strontium 109 

Strychnine 127,-  136,  157 

Sublimation 80 

Subnitrate  of  Bismuth 142 

Sugar,  Cane 116 

"      Grape 117,  155 

"      of  Lead" 99 

Sulphur 79 

Sulph-Salts 142 

TAPIOCA 116 

Tar 70 

Tartar  Emetic 91,  124 

Tin 103 

Turpentine 133 

Type-metal 143 

VERDIGRIS . . .  100 

Vermilion ...   96 

Ventilation 68 

Vinegar 121,  136 

Vitriol,  Blue 100 

"      Green 102 

"      Oil  of :    ....  81 

Volatile  Oils 132 

WATER 13,  14,  37,  53,  139 

"      of  Crystallization 55 

"      type 26,  125 

White-lead 99 

Wines 119 

Woody  Fiber 116 

YEAST 118,  123 

ZINC..  ..103 


THEORETICAL    CHEMISTRY. 


CHAPTER     I. 


INTRODUCTION. 

MATTER  exists  in  three  states: — 

1.  Solid:  Ex.,  iron,  lead,  ice. 

2.  Liquid:  Ex.,  mercury,  bromine,  water. 

3.  Gaseous:  Ex.,  hydrogen,  air,  steam. 

Nearly  all  substances  ordinarily  in  the  solid  state  may,  by  applying 
heat  (and  removing  pressure),  be  made  first  liquid  and  then  gaseous. 
Nearly  all  gases,  by  cold  and  pressure,  may  be  made  first  liquid  and  then 
solid 

A  change  which  merely  converts  a  solid  to  a  liquid,  or  a  liquid  to  a 
gas,  or  vice  versa,  however  wonderful  such  change  may  be,  is  not  a 
chemical,  but  a  physical  change.  Ex.,  Ice  may  be  heated  and  converted 
into  water  a  liquid,  and  then  into  steam,  a  gas. 

All  such  changes  are  studied  in  Phy-ics,  not  in  Chemistry.  Chemistry 
deals  with  such  changes  only  incidentally. 

The  molecules  (small,  invisible  particles)  of  a  solid  move  with  diffi- 
culty upon  each  other  The  molecules  of  a  liquid  move  readily  upon 
each  other,  so  that  the  liquid  assumes  the  shape  of  the  vessel  holding  it. 
The  molecules  of  gas  have  an  apparent  repulsion  for  each  other,  so  that 
a  gas,  regardless  of  its  specific  gravity  (i.  e.  whether  light  or  heavy), 
escapes  from  an  open  vessel  and  diffuses  itself  throughout  the  surround- 
ing space. 

We  learn  many  things  incidentally  about  solids  and  liquids  before 
studying  either  Physics  or  Chemistry.  We  know  comparatively  little 
about  gases,  except  about  the  gaseous  ocean  of  air  at  the  bottom  of 
which  we  live.  To  the  chemist,  however,  the  gas  is  in  many  respects 
the  simplest  state  of  matter  and  the  most  convenient  for  him  to  exam- 
ine critically. 


10  CHEMICAL   PRIMER. 


CHAPTER     II. 


The  Atomic  Theory  divides  matter  into: — 

1.  Mass. — Any  portion  of  matter  appreciable  by  the 
senses. 

2.  Molecule. — The  smallest  particle  of   matter  that 
can  take  part  in  a  mere  physical  change.     It  may  exist 
alone. 

3.  Atom. — The  smallest  particle  of  matter  that  can 
take  part  in  a  chemical  change.     An  atom  does  not  exist 
alone.     Atoms  compose  molecules ;  i.e.,  two  or  more  atoms 
make  a  molecule. 

Chemistry  treats  of  the  atomic  condition  of  matter 
and  especially  of  atomic  changes. 

It  will  be  inferred  from  the  definitions  that  a  mass  may  be  very  large 
or  exceedingly  small,  also,  that  the  molecule  and  the  atom  are  not  visi- 
ble even  with  the  aid  of  the  most  powerful  microscope,  otherwise  they 
would  be  "appreciable  by  the  senses." 

Chemistry  treats  of  more  subtle  changes  than  physics.  If  the  mol- 
ecule is  not  broken  up  and  the  atoms  set  free  to  form  new  combinations, 
it  matters  not  how  violent,  or  how  wonderful  the  change  may  be,  it  is 
purely  physical  and  in  no  sense  chemical. 

Of  course,  atoms  "exist  alone"  during  the  instant  of  chemical  change. 
One  atom  may  rarely  make  a  molecule.  At  this  stage,  however,  the 
pupil  should  not  trouble  himself  with  exceptions. 

NOTE. — We  know  that  there  are  masses  and  molecules,  but  we  do  not 
know  that  there  is  any  such  thing  as  an  atom.  More  than  this  we  do 
not  care  whether  there  is  or  not.  The  atom  is  to  chemistry  what  the  x, 
01  unknown  quantity,  is  to  algebra.  It  enables  us  to  accomplish  results 
which  otherwise  would  be  impossible.  The  Atomic  Theory  is  as  useful 
in  the  study  of  chemistry  as  the  Arabic  numerals  are  in  the  study  of 
arithmetic. 


THEORETICAL   CHEMISTRY.  11 


CHAPTER     III. 


An  Element  is  a  substance  whose  molecules  contain 
atoms  of  one  kind  only ;  therefore  it  cannot  be  separated 
into  two  or  more  different  kinds  of  substances.  Ex.,  gold, 
lead,  hydrogen. 

A  binary  compound  is  a  substance  which  has  two  dif- 
ferent kinds  of  atoms  in  its  molecule,  and  therefore  can 
be  separated  into  two  different  kinds  of  substances.  Ex., 
water,  common  salt. 

A  molecule  of  hydrogen  may  be  represented  thus  [  H  H  J  in  which 
each  H  represents  an  atom  of  hydrogen  and  the  boundary  line  simply 
the  fact  that  the  two  atoms  are  bound  together  by  chemical  bonds  into 
one  molecule. 

It  is  well  to  remember  that  we  can  only  represent  a  point  on  the  board, 
or  upon  paper,  we  cannot  make  one.  We  only  represent  lines,  we  can- 
not make  them.  The  "point"  on  the  board  is  infinitely  too  large  for  a 
real  point.  So  the  H  above  is  too  large  to  represent  with  any  suggestive- 
ness  as  to  *ize  an  atom  of  hydrogen.  Let  the  pupil  imagine  in  place  of 
the  two  H's  in  the  molecule  two  infinitesimally  small  particles  of  hy- 
drogen side  by  side.  These  are  precisely  alike ;  are  mysteriously  held 
together  by  some  peculiar  law  allied  to  gravitation,  and  act  in  most 
cases,  i.  e.  in  all  physical  cases,  as  one  particle.  The  two  atoms  taken 
together  (the  one  molecule  of  hydrogen)  must  be  much  too  small  to  be 
seen  even  with  a  microscope,  and  there  must  be  many  millions  of  mol- 
ecules in  a  very  small  vessel  full  of  hydrogen. 

A  molecule  of  water  may  be  represented  thus  |_HpHj  or  more 
briefly,  thus  |  H2O  |  or  still  more  briefly  by  omitting  the  boundary 
line,  thus  H.,0.  This  means  that  in  a  molecule  of  water  there  are  two 
atoms  of  hydrogen  (precisely  alike)  and  one  atom  (unlike  the  other  two) 
of  oxygen. 


12  CHEMICAL   PRIMER. 

An  attentive  student  will  readily  grasp  the  condition  of  matter  which 
the  Atomic  Theory  supposes,  both  as  to  the  elements  and  as  to  binary 
compounds.  The  immense  value  of  the  theory  will  be  seen  as  it  is  de- 
veloped into  practical  results  in  the  following  chapters. 

Practically  the  representation  H.^0  means  that  two  parts  by  volume  of 
hydrogen  unite  with  one  part  by  volume  of  oxygen  to  form  the  binary 
compound  which  we  call  water.  (Take  this  for  granted  now;  we'll 
prove  it  by  and  by.  See  WATER,  index.)  Thus,  two  gases  unite  to 
form  a  liquid.  But  this  is  a  chemical  change,  because  the  atoms  of  the 
molecules  of  hydrogen  and  of  oxygen  are  disturbed,  their  molecules 
being  broken  up  to  form  new  molecules  of  a  different  substance,  water. 
The  change  may  be  represented  thus: — 

j  HH!    PHHJ  +  [jpp'J  —  FH^O]   ["H/H 

This  means  that  two  molecules  of  hydrogen  and  one  molecule  of  oxy- 
gen break  up  into  separate  atoms  and  then  instantaneously  reunite  into 
two  molecules  of  water. 

The  atomic  change  (beginning  at  the  instant  when  the  molecules  are 
broken  up)  may  be  written  thus: — 

H2  +  0  H20 

Two  atoms  One  atom  One  molecule 

of  hydrogen  of  oxygen  of  water 

Chemical  changes  are  called  Reactions.  For  all  ordinary  purposes 
the  atomic  reaction  is  correct.  As  it  is  not  nearly  so  difficult  as  the 
molecular  reaction  (first  above)  it  alone  will  be  used  in  this  book. 

There  are  about  sixty -seven  elements  known,  and  these 
may  be  considered  the  alphabet  of  chemistry.  From  these 
all  chemical  compounds  are  formed,  as  words  from  letters. 


THEORETICAL    CHEMISTRY.  13 


CHAPTKR     IV. 


Atoms  of  different  elements  differ  in  three  essential 
respects : — 

1.  In  weight. 

2.  In  quality. 

3.  In  strength. 

The  First  Difference  needs  no  explanation.  When  we  say  that 
atoms  differ  in  weight,  we  mean  that  they  differ  in  weight.  (Atoms  of 
the  same  element  have  always  the  same  weight. ) 

The  Second  Difference  needs  explanation.  The  quality  of  meat 
may  be  determined  by  eating  it,  and  the  quality  is  said  to  be  gowl  or 
bad.  The  quality  of  cloth  may  be  told  by  wearing  it,  and  the  quality  of 
cloth  is  also  said  to  be  good  or  bad,  as  the  case  may  be. 

The  quality  of  an  atom  is  determined  by  electricity,  and  the  atom 
is  said  to  be,  not  good  or  had,  but  positive  or  negative. 

If  a  current  of  electricity  from  two  or  more  of  Bunsen's  quart  cups  be 
passed  through  the  binary  compound  water,  the  water  will  be  decom- 
posed and  bubbles  of  gas  will  appear  at  each  pole.  If  the  gas  from  the 
positive  pole  be  collected  (see  Fig.  No.  1)  and  tested,  it  will  prove  to  be 
oxygen.  If  the  gas  from  the  negative  pole  be  collected  and  tested,  it 
will  prove  to  be  hydrogen  and  will  have  twice  the  volume  of  the  oxygen. 

NOTE.— The  water  should  be  acidulated  slightly  with  sulphuric  acid. 
The  hydrogen  will  always  have  a  little  more  than  twice  the  volume  of 
the  oxygen,  because  the  liberated  oxygen  is  more  soluble  in  (the  remain- 
ing) water  than  the  hydrogen.  The  pupil  may  learn  right  here  that  a 
gas  can  be  dissolved  in  water  just  as  w<  II  as  a  solid.  The  nature  of  a  mere 
solution  will  be  explained  hereafter.  [See  Chap.  XV.] 

..^  ^«~p    e./L-  /^^.  «^    A, 

^^t^M^G     #»-     t*  n>  .'     \ 

"....••« 


14 


CHEMICAL  PRIMER. 


Fig.  1.     A  A— Platinum  Ends  (poles,  or  electrodes). 

The  law  of  electricity  being  that  "like  electricities  repel  each  other  and 
unlike  attract" — as  oxygen  goes  to  the  positive  pole,  it  is  negative  to 
hydrogen,  and  as  hydrogen  goes  to  the  negative  pole,  it  is  positive  to 
oxygen. 

Thus,  by  means  of  a  battery  acting  upon  their  compounds,  the  ele- 
ments may  be  arranged  with  reference  to  their  "quality" — but  an  atom 
of  an  element  is  always  positive  or  negative,  not  absolutely,  but  rela- 
tively. 

For  example,  if  we  arrange  in  line  sixty-seven  boys  from  north  to 
south,  the  first  boy  would  be  a  north  boy  to  any  other.  The  second  boy 
would  be  a  south  boy  compared  with  thejirst,  but  a  north  boy  compared 
with  the  third.  The  tenth  boy  would  be  a  south  boy  compared  with  the 
fourth,  but  a  north  boy  compared  with  the  fifteenth.  Any  boy  would 
be  a  south  boy  to  all  boys  north  of  himself,  but  a  north  boy  to  all  boys 
south  of  himself. 

Thus,  the  elements  are  arranged  in  line  according  to  their  ' '  quality, " 
oxygen  standing  first,  being  most  negative.  (See  Reference  Table  No.  1.) 
This  difference  in  "quality"  is  of  the  utmost  importance  in  chemistry. 

The  Third  Difference  may  be  explained  by  an  illustration. 

If  one  man  can  hold  a^  100-lb.  weight,  we  may  call  his  strength  one. 
Then,  if  another  man  can  hold  two  100-lb.  weights,  his  strength  would 
be  two,  and  it  would  take  two  of  the  first  kind  of  men  to  match  one  of 
the  second  kind.  If  a  third  man  can  hold  three  100-lb.  weights,  his 
-^•N*-  -*•/>*_  _*-c-*-i^^  &Poi-4t-^  t  ._  *'.. .  *!».*  *Ww«*^ 


THEORETICAL    CHEMISTRY.  15 

strength  would  be  three,  and  it  would  take  three  of  the  first  kind  of  men 
to  match  one  of  the  third.  But  how  shall  we  match  the  second  kind 
of  men  and  the  third  kind  ?  Evidently,  three  of  the  second  kind  would 
match  two  of  the  third  kind.  If  a  fourth  man  can  hold  four  100-lb. 
weights,  his  strength  will  be  four ;  etc. 

The  strength  of  atoms  is  measured,  not  by  100-lb.  weights,  but  by  the 
strength  of  hydrogen  atoms.  The  strength  of  the  hydrogen  atom  is 
taken  as  one.  The  strength  of  those  elements  whose  atoms  each  require 
one  atom  of  hydrogen  to  match  them  is  one ;  of  those  elements  whose 
atoms  each  require  two  atoms  of  hydrogen  to  match  them,  the  strength 
is  tiro ;  of  those  whose  atoms  require  three  atoms  of  hydrogen,  the 
strength  is  three,  etc. 

These  elements  are  called  respectively  monads  (1), 
dyads  (2),  triads  (3),  tetrads  (4),  pentads  (5),  hexads  (6), 
and  heptads  (7).  This  strength  of  the  atoms  is  often 
expressed  adjectively  by  the  terms,  univalent  (1),  bivalent 
(2),  trivalent  (3),  quadrivalent  (4),  pentivalent  (5),  etc. 


CHARTER    V. 


The  names  of  the  elements  are  abbreviated  in  chemical 
language.  O  is  the  symbol  for  oxygen,  S  for  sulphur,  Sb 
for  antimony  (Latin,  stibium),  etc.  The  dictionary  will 
give  the  Latin  name  from  which  a  number  of  the  symbols 
are  derived. 

The  following  Reference  Table  exhibits  the  symbols  of 
the  most  important  elements  and  the  three  essential  dif- 
ferences of  their  atoms:  — 

. 

" 


i  . 


REFERENCE   TABLE    Nth  1. 


SYMBOL. 

QUALITY. 

Shown  by  order  of  names. 

ATOMIC 
WEIGHT. 

STRENGTH. 

Negative  End. 

o 

Oxygen  - 

16 

2 

^•6 

Sulphur 

32 

2      ^ 

N 

Nitrogen- 

14 

3  ,-! 

(F 

Fluorine 

19 

1     ti^ 

Cl 

Chlorine 

35.5 

1          >    0 

fir 

Bromine 

80 

i    &|7 

I 

Iodine                727 

1     o£  | 

CN 

Cyanogen*               26 

1   ill 

Se 

Selenium                79 

2    a 

*P 

Phosphor*^  -           31 

5—  (3) 

\A.s 

Arsenic  iu/;-             75 

3-(5) 

Or 

Chromium               52.5 

2 

Boron 

11 

3 

*' 

j  C 

Carbon   - 

12 

4-(2) 

1 

Sb 

Antimony 

122 

3—  (5) 

**  . 

Si 

Silicon 

28 

4 

H 

HYDROGEN 

1 

1 

Au 

Gold    4 

196.6 

3  (i) 

I 

W 

Pt 

Platinum 

197 

4-(2) 

03 
•***• 

t  J3g 

Mercury  - 

200 

2   (Hgaadyad) 

-*• 

:  Ag 

Silver 

108 

1 

Cu 

Copper  Q 

63.5 

2   (Cu2adyad). 

Bi 

Bismuth 

210 

3 

Sn 

Tin   j 

118 

4-(2) 

Pb 

Lead  -^ 

207 

2-(4) 

Co 

Cobalt 

59 

2 

Ni 

Nickel 

59 

2 

\Fe 

Iron   § 

-    56 

2   (Fe2ahexad) 

Zn 

Zinc 

65 

2 

Mn 

Manganese 

55, 

2-(4) 

Al 

Aluminum 

27.5 

A12  a  hexad 

Mg 

Magnesium 

24 

2 

Ca 

Calcium 

40 

2 

Sr 

Strontium 

87.5 

2 

Ba 

Barium 

137 

2 

s 

i  fNa 

Sodium 

23 

1 

x  K 

Potassium 

39 

1 

\ 

i  VH4N 

Ammonium* 

18 

1 

Positive  End. 

*Not  elements.     (See  Chap.  VI.) 


>' 


THEORETICAL   CHEMISTRY.  17 


CHAPTER    VI. 


A  binary  compound  is  named  by  placing  the  positive 
element  first  and  changing  the  ending  of  the  negative  into 
ide. 

EXAMPLES. 

Formula.  Xame. 

Na  Cl  —  sodium  chloride. 
K.;  O     =  potassium  oxide. 

It  will  be  noticed  that  sodium  and  chlorine  are  both  monads  (see 
strength  in  Reference  Table  No.  1),  and  therefore  it  requires  one  atom 
of  each  to  match  the  other  in  the  molecule,  as  in  the  first  example.  In 
the  second  example,  potassium  is  a  monad  (see  TABLE),  but  oxygen  is  a 
dyad,  therefore  it  takes  tioo  atoms  of  potassium  to  match  one  of  oxygen 
in  the  molecule. 

Again,  in  putting  dyads  and  triads  together,  we  must  take  three  dyads 
to  match  two  triads  in  the  molecule,  a  strength  of  two  times  three  equal- 
ing a  strength  of  three  times  two.  * 

EXAMPLE. 

Asa  S3  —  arsenicum  sulphide. 
Again,  two  dyads  must  be  taken  to  match  one  tetrad. 

EXAMPLE. 

C  O2  =  carbon  oxide. 

Aluminum  is  peculiar.  A  single  atom  is  never  found  in  any  molecule, 
but  two  atoms  together  have  a  strength  of  six. 

EXAMPLE. 

Al-i  C16  =  aluminum  chloride. 
Five  dyads  must  be  taken  to  match  two  pentads. 

EXAMPLE. 
?2  S5  =  phosphorus  sulphide. 


18 


CHEMICAL  PRIMER. 


NOTE.— Just  as  we  sometimes  say  "the  father  of  Mary,"  instead  of 
"Mary'fe  father,"  the  older  chemists  say  "sulphide  of  phosphorus,'' 
instead  of  "phosphorus  sulphide."  They  also  express  the  same  by 
"sulphwel  of  phosphorus,'  or  "sulphuretted  phosphorus." 

Atoms  of  two  or  more  elements  bound  together  by 
chemical  bonds  so  closely  as  to  act  as  one  atom  in  the 
formation  of  compounds,  form  a  Compound  Radical. 

Two  very  important  compound  radicals  are  inserted  in  the  Reference 
Table  and  linked  with  the  elements  with  which  they  are  closely  allied. 
Their  compounds  with  a  single  element  are  considered  and  named  as 
binaries,  though  they  contain  three  different  kinds  of  atoms. 

EXAMPLES. 

K  CN  =  potassium  cyanide. 
(HiNJ^S  =  ammonium  sulphide. 
H4  N    CN  —  ammonium  cyanide. 

NOTE. — The  pupil  should  write  the 
formulas  and  names  of  a  great  many 
binary  compounds,  putting  the  atoms 
together  according  to  the  strength  in  the 
Reference  Table.  Be  careful  that  the 
multiplications  make  the  positives  match 
in  strength  the  negatives,  as  in  the  exam- 
ples. It  does  not  matter  if  many  of  the 
compounds  are  merely  theoretical.  It  is, 
however,  a  great  gain  at  this  point  to 
have  as  many  binaries  as  combine  according 
to  the  first  strength  given  in  the  Table,  shown 


Fig.  2 


to  the  scholars.  For  instance,  a  substance  might  be  shown  and  the 
class  told  that  it  was  a  compound  of  sulphur  and  sodium.  They  should 
then  all  write  labels  for  the  bottle  containing  it,  giving  formula  and 
name,  as  in  Fig.  2. 


4.*AiA~ 


THEORETICAL    CHEMISTRY.  19 


CHAPTER    VII. 


Ic  and  Ous  Binaries. 

These  may  be  introduced  by  an  illustration:  In  one  of  our  Eastern 
townships  lived  a  man  who  was  afflicted  with  periodic  insanity.  When 
in  his  right  mind  (ordinarily),  he  had  the  strength  of  his  brother.  He 
could  be  called  a  monad.  In  one  of  his  insane  fits  he  carried  three  men 
upon  his  back  over  a  gate  five  boards  high.  He  became  a  very  decided 
triad,  you  see. 

Xow,  the  Reference  Table  No.  1  gives  the  "strength"  of  chlorine 
one,  i.  e.,  as  a  monad  —  but  sometimes  it  acts  with  a  strength  of  three, 
i.  e.,  as  a  triad  (sometimes  as  a  pentad,  or  even  as  a  heptad). 

Carbon  is  given  a  strength  of  four,  and  this  it  ordinarily  has  —  but 
sometimes  it  acts  with  a  strength  of  only  two.  Thus,  it  forms  two 
binary  compounds  with  oxygen,  C0.2  and  CO.  Evidently,  if  we  say 
carbon  oxide,  we  shall  not  know  which  is  meant,  because  the  name  may 
apply  to  either. 

As  a  rule,  an  atom  with  an  even  strength  never  has  an  odd  strength, 
also,  an  atom  with  an  odd  strength  never  has  an  even  strength.  The 
strength  increases  or  decreases  by  tioos.  This  will  be  noticed  as  we  pro- 
ceed. 

The  column  in  parenthesis  in  Tabte  under  STRENGTH,  includes  all  the 
variation  that  beginners  will  need  for  reference  in  writing  binaries. 

We  must  invent  some  way  to  distinguish  the  different  compounds, 
when  an  element  acts  with  different  strengths. 

When  the  positive  takes  more  of  the  negative,  it  has 
the  ending  ic,  when  it  takes  less  of  the  negative,  it  has 
the  ending  OUS. 

EXAMPLES. 

C  O2  =  carbonic  oxide, 
C  O  =  carbonous  oxide. 


U 


20  CHEMICAL  PRIMER. 

When  the  positive  takes  more  of  the  negative  than  in  the  ic  com- 
pound, it  has  the  prefix  per  (from  hyper  =  more);  when  it  takes  less  of 
the  negative,  than  in  the  ou's  compound,  it  takes  the  prefix  hypo  (under). 

EXAMPLES. 

Cl«  0  =  hypo-chlorous  oxide.  (Cl  a  monad) 

C12  03  —  chlorous  oxide.  (Cl  a  triad) 

C12  O5  =  chlorzc  oxide.  (Cl  a  pentad) 

C12  07  —  per-chloric  oxide.  (Cl  a  heptad) 

NOTE.  —  Per  and  hypo  are  rarely  prefixed  to  the  negative  instead  of 
to  the  positive.  Few  elements  form  hypo-  and  per  binaries,  and  the 
pupil  will  be  troubled  very  little  with  them.  They  are  given  here  so 
that  if,  in  the  larger  text-books,  he  sees  hypo-  and  per-binaries  men- 
tioned, he  may  have  some  idea  of  what  is  meant. 

The  scholar  should  here  solve  many  problems,  such  as  the  following:  — 

1.  Put  together  sulphur  and  antimony  to  form  two  compounds,  giving 
antimony  a  strength  in  the  first  compound  as  in  the  Table,  and  in  the 
second  compound  a  strength  as  in  the  parenthesis.     Name. 

Ans.     Sb2  S3  =  antimonow,s  sulphide. 
Sb2  S5  —  antimomc  sulphide. 

2.  Put  together  iodine  and  mercury,  giving  mercury  a  strength,  first, 
as  in  Table;  second,  as  in  the  parenthesis.     Name. 

Ans.     Hg  I2  —  merciin'c  iodide. 

Hg.2  12  =  me'rcurozw  iodide. 

NOTE.  —  In  this  last  compound,  mercury  seems  to  be  a  monad,  i.  e.,  it 
seems  to  change  from  the  even  to  th§  odd  strength.  A  few  of  the  other 
elements  do  the  same  thing,  as  you  will  see.  For  practical  purposes, 
this  last  formula  has  sometimes  been  written  Hg  I  =  mercurows  iodide, 
but  it  is  better  to  write  as  above. 

The  ic  and  ous  compounds  of  the  same  elements  often  differ  very  much 
in  physical  and  chemical  properties.  You  will  see,  by  looking  at  the 
samples  from  the  laboratory,  that  mercuric  iodide  is  red,  while  mercur- 
ous  iodide  is  green.  Again,  carbomc  oxide  is  not  poisonous,  while  car- 
bonows  oxide  is  poisonous. 

Notice  that  for  gold,  copper,  tin,  lead,  and  iron,  the  adjectives  (from 
Latin)  aurous,  cuprous,  stannous,  plumbous,  and  ferrous,  respectively, 
are  used  in  one  compound,  and  auric,  cupric,  etc.,  in  the  other. 


**P 


THEORETICAL    CHEMISTRY.  21 


A  binary  may  be  named  by  prefixing  the  Greek  num- 
erals (mony  di,  tri,  tetra.  etc).  In  all  cases  where  a  mis- 
take would  be  likely  to  occur,  this  very  exact  method  is 
used. 

EXAMPLES. 

C  O  =  carbon  monoxide,     (pus.) 
C  O2  —  carbon  dioxide,     (ic.) 
Fe.,,  O3  =  di-ferric  trioxide.      (ic.) 

NOTE. — The  older  chemists  used,  as  a  rule,  ver  and  proto  for  ic  and 
ous  respectively,  as: — 

Fe  O  —  prof  oxide  of  iron,  instead  of  ferrous  oxide. 
Fe^  O3  •==•  pe?-oxide  of  iron,  instead  of  ferric  oxide. 

Instead  of  ous,  the  prefix  sub  was  also  used,  as:  Hg2  C12  =  s«6chlo- 
ride  of  mercury. 

Compounds,  in  which  tnere  were  two  of  the  positive  to  three  of  the 
negative,  often  took  the  prefix  sesqui  (one  and  one-half),  as: — 
Fea  O3  =  sesquioxide  of  iron. 

There  is  still  another  name  which  the  unfortunate  druggist  must 
learn,  a  Latin  name  with  which  he  labels  his  bottles.  (See  Chap.  XIII  , 
NOTE.  ) 


Write  the  names  of  the  following,  using  ic  and  ous  in  the  first  three 
columns  and  the  Greek  prefixes  in  the  last  column: — 


AsA  = 

Au  C13  - 

Sb2o5  -  * 

Mn02  = 

AsA  = 

Fe,Cl6  = 

Pt  ci,  - 

C02  - 

SnS2  = 

Hg2Cl2  - 

Sb2S3  = 

PC15  - 

SnS  = 

Au  Cl  = 

Pt  Br2  = 

P  Cl,  - 

PA  = 

Cu2O  = 

CO  = 

Fe2S3  = 

PA  = 

CnO  = 

FeS  = 

CO  = 

Hg  Cl,  = 

Hg  2  CN  = 

Pb  Br4  = 

cs,  = 

HgS  = 

Pb  I,  - 

CuS  - 

PbO  = 

*4A*  ^.^. 

*~w*     ±^<4 

- 

? 

V                              ' 

ct^»^^JU 

M^^l.     £-          5L. 

.^     ^ 

22  CHEMICAL   PRIMER. 


CHAPTER    VIII. 


Inspection  of  the  following  questions  and  the  methods 
of  solution  will  reveal  the  great  value  of  the  Atomic 
Theory  to  the  chemist,  and,  indeed,  to  the  world  of 
industry. 

1.  In  116  kilograms*  of  mercuric  sulphide  (Hg  S)  how 
much  mercury? 

Hg  —  200  atomic  weight  (see  Tablej. 
S    =     32 


Hg  S  —  232  molecular  weight. 

corresponds  to 

232  kgs.  of  Hg  S  =  200  kgs.  of  Hg. 

1         "         "       =  irk  of  200  kgs.  of  Hg. 
116         "         "      =  HI  of  200     " 

HI  of  200  =  100  kgs.  of  Hg      Am. 

2.    How  much  lead  chloride  (Tb  Cla)  could  be  made 
from  50  grams  of  lead? 

Pb  =  207  at.  wt. 
6,  =      71      " 

Pb  Cla  =  278  mol.  wt. 
207  Pb  =  278  PbCl2 

1    "    =  ^  of  278  Pb  01, 
50   "    =  JVr  of  278      "      =  67/oV  grams.    Ans. 


It  will  be  noticed  that  there  are  two  distinct  kinds  of  questions.    The 
first  gives  the  weight  of  the  binary  and  requires  the  weight  of   the 

*See  metric  system,  Index. 

i 


THEORETICAL    CHEMISTRY  23 


element  The  second  gives  the  weight  of  the  element  and  requires  the 
weight  of  the  binary.  In  the  first  class  of  questions  of  course,  the 
answer  is  less  than  the  given  weight.  In  the  second  class  the  answer  is 
more  than  the  given  weight.  After  obtaining  the  molecular  weight  by 
the  addition  of  the  atomic  weights,  set  in  the  left  hand  number  of  the 
first  equation  the  weight  (atomic  or  molecular)  of  the  given  quantity  as  in 
the  example. 

3.  From  one  metric  ton  of  the  iron  ore  hematite  (Fe2  O3,  ferric  oxide), 
how  many  kilograms  of  iron  could  be  obtained,  provided  the  hematite 
contained  25  per  cent,  of  earthy  impurities,  or  waste  ? 

1  M.  T.  =  1000  kgs. 
25  per  cent,  waste  leaves      75  per  cent. 

750  kgs.  of  pure  ore. 
Fe.2  =  112  at.  wt. 
03   =     48      " 

Fe.2  03  =  160  mol.  wt. 

160Fe2O3  =  112Fe 

1      '«       =TJTrofll2Fe 
750      "      =  jf  g  of  112  Fe  =  525  kgs.  iron.     Am. 

NOTE. — The  pupil  should  perform  very  many  problems  similar  to  the 
above.  To  show  one  common  process  of  getting  the  element  from  the 
ore,  heat  some  lead  oxide  (litharge)  on  charcoal  (carbon)  in  the  blow- 
pipe flame.  The  carbon  takes  the  oxygen  from  the  lead,  forming  car- 
bonic oxide  (C  O2)  and  leaves  the  lead  free,  i.  e.,  not  combined  with 
any  other  element  (see  Exp.  50). 

4.  How  much  lead  in  100  kgs.  of  lead  oxide  (Pb  O)?    Am.  92^-f-f. 
"  5.  One  M.  T.  of  lead  would  make  how  many  kilograms  of  litharge? 

Ana.  1077^Vr- 

6.  How  much  silver  in  50  kgs.  of  silver  chloride? 

7.  How  much  silver  chloride  must  be  taken  to  obtain  from  it  50  kgs. 
of  silvei  ? 

8.  How  much  mercury  would  be  required  to  make  150  kgs.  of  vermil- 
ion (mercuric  sulphide)? 

9.  How  much  lead  in  one  metric  ton  of  plumbous  chloride  ? 

10.  How  much  gold  in  500  grams  of  auric  chloride9 


24  CHEMICAL   PRIMER. 


CHAPTER     IX. 


A  ternary  compound  is  one  having  three  different 
kinds  of  atoms  in  its  molecule,  and  therefore  can  be  sep- 
"  I  arated  into  three  different  kinds  of  substances. 

Most  ternaries  contain  oxygen  as  a  connecting  element ; 
it  is  therefore  omitted  in  the  name.  It  is  understood  to 
be  the  connecting  element,  unless  otherwise  mentioned 
(see  Sulph-Salts,  Index).  It  is  not  omitted  in  the  form- 
ula. 

A  ternary  is  named  by  placing  the  positive  first  and 
(the  O  being  omitted)  the  negative  last,  -with  the  ending 
changed  into  ate. 

EXAMPLES. 

K  Cl  Oa  =  potassium  chlorate. 
H2SO4    =  hydrogen  sulphate. * 

As  in  binaries,  we  have  different  compounds  of  the  same  three  ele- 
ments, and  so  must  have  different  names. 

When  the  0  is  less  (relatively  to  the  negative)  than  in  the  ate  com 
pound,  the  negative  takes  the  ending  ite. 

EXAMPLES. 

K  Cl  O3  —  potassium  chlorate. 
K  Cl  02  =  potassium  chlorite. 

Rarely  the  0  may  be  less  than  in  the  ite  compound,  when  hypo 

it<  is  used.      Sometimes  the  O  is  more  than  in  the  ate  compound,  when 

per ate  is  used. 

EXAMPLES. 

K  Cl  O  —  potassium  hypo- chlorite. 
K  Cl  02  =  potassium  chlorite. 
K  Cl  03  =  potassium  chlorate. 
K  Cl  04  =  potassium  per-chlorate. 


THEORETICAL    CHEMISTRY.  25 


As  in  binaries,  the  hypo-  and  per- ternaries  are  very  few  and  will  trouble 
the  student  very  little.  The  ite  compounds  are  also  few  in  comparison 
with  the  ate.  This  will  be  a  good  rule  for  beginners:  "Call  every  ter- 
nary an  ate  links*  you  have  reason  to  call  it  an  ite. " 

Name  the  following: — 

H3  PO.  =  ?  Mg  S04  =    I      Which  is  the  ate  and 

TT  xrn    -  Mrr^n   —    hwhich   the  ite  com- 

KJsO.  _  MgS03_    fpound? 

Ca  2  HO  —  Ca3  2  P04  = 

XOTE.  — Don't  ask  why  the  atoms  in  the  above  are  matched  or  multi- 
plied as  they  are.  You  will  not  understand  this  till  you  have  completed 
Chap.  XII. 


CHAPTER    X. 


There  are  three  great  classes  of  ternaries,  with  which 
the  scholar  should  early  become  familiar,  viz. : — acids, 
bases,  and  salts. 

Acids  are  generally  sour,  and  turn  blue  vegetable  colors 
(such  as  litmus)  red. 

Bases  (those  that  are  soluble  in  water  are  called  alka- 
lies; turn  red  litmus  paper  blue. 

Acids  and  bases  are  chemical  opposites.  They  attack 
and  destroy  each  other,  forming  salts  (and  water).  This 
power  of  forming  a  salt  with  its  opposites  is  the  true  test 
for  an  acid  or  a  base.  The  test  with  litmus  paper  is  a 
very  good  one  and  usually  answers. 

NOTE. — The  pupil  should  here  test  a  number  of  acids  and  bases  with 
litmus  paper.  Of  course,  acids,  bases,  and  salts  may  exist  in  either  of' 
the  three  physical  states:  solid,  liquid,  or  gaseous.  Solid  or  gaseous 
acids  and  bases  must  be  dissolved  in  water  before  testing,  or  the  litmus 
paper  wet  (which  is  the  same  thing). 

-V>J  •  .-*•"      £**»»,    w£c^"i.c*t-*y, 

' 


26  CHEMICAL  PRIMER. 


Acids,  bases,  and  salts  are  said  to  be  formed  on  the 
water-type,  thus:— 

I  H  H  6      =  molecule  of  water. 

[_H,  a  negative  element  and  O  |  =  a  molecule  of  an 
acid. 


A  positive  element.  H  and  O      —  a  molecule  of   a 
base. 


A  positive  element,  a  negative  element  and  O  j    — 


a  molecule  of  a  salt. 

In  the  above  water-type,  by  a  negative  element  is  meant  one  negative 
to  hydrogen,  and  by  a  positive  element  one  positive  to  hydrogen. 

In  the  Reference  Table,  if  the  element  is  above  hydrogen,  it  is  nega 
tive  in  forming  acids,  bases,  or  salts;  if  below  hydrogen,  it  is  positive. 

Write  the  name  of  the  following,  and  mark  as  acid,  base,  or  salt. 
(Consult  Table  No.  1.  A  large  figure  multiplies  all  atoms  that  follow 

K  Cl  03  •=.  potassium  chlorate  •=•  salt. 
H2  S  04  —  hydrogen  sulphate  —  acid. 

Ca  2  HO  =  calcium  hydrate  =  base. 

Na2S04  =  ?  (H4N)2  S0±=  Na  HO  =  Ba  2  HO  =: 

HN03  =  H2S03=  Mg32P04  =       PbCr04  = 

KN03  =  Ag3As04=  NaC103:=          H3  B03= 

-  » 

NOTE.  —  The  division  into  positive  and  negative  elements  is  not  always 
made  at  hydrogen.  Thus,  zinc  is  usually  positive  in  forming  by  the 

+ 
water-type,  and  Zn  2  HO  zinc  hydrate  =  base—  but  rarely,  when  in  pres- 

ence of  a  stronger  positive  element,  as  potassium:  Zn  2  HO  zinc  hydrate 
becomes   (or  may  be  considered)  H2  Zn  0^  —  hydrogen  zincate  =  an 

acid;  and  we  have  the  salt  K^  Zn  O.,  =  potassium  zincate,  in  which  Zn 
is  negative  not  to  H  but  to  K.     So  chromium  usually  by  the  water-  type 

acts  as  a  negative  element,  and  H2  Cr  O4  —  hydrogen  chromate  =•  an 

'   \  ^ 


-K/o.    'J  or  . 


THEORETICAL    CHEMISTRY.  27 


acid,  but  rarely  chromium  acts  as  a  positive  element,  and   we  have 

Cr,  6  HO  =•  chromium  hydrate  =  a  base.  The  pupil  at  this  stage, 
however,  should  not  attempt  to  deal  with  exceptions,  but  should  treat 
the  rule  given  as  though  it  were  absolute,  and  should  consider  all  elements 
above  hydrogen  as  negative  and  all  elements  below  hydrogen  as  positive 
in  the  formation  of  acids,  bases,  and  salts.  After  deciding  from  the 
formula,  test  acids  and  bases  by  litmus  paper,  and  thus  prove  the  rule. 
This  water  type  should  be  so  thoroughly  mastered  that,  having  t/ie  Ref- 
erence Table  before  you,  you  can  tell  at  a  glance,  on  seeing  the  formula, 
whether  the  ternary  is  an  acid,  base,  or  salt. 


CHAPTER     XI 


It  will  be  noticed  that  in  the  Reference  Table  four  neg- 
ative elements  and  one  compound  radical  are  linked  to- 
gether. These  elements  are  called  the  haloid  elements 
(or  halogens  —  salt-forming),  because  they  form  salts  (and 
acids)  without  oxygen,  i.  e.,  they  form  binary  salts  and 
acids. 

EXAMPLES. 

H  Cl  =  hydrogen  chloride  —  a  binary  acid. 
Mg  C12  =  magnesium  chloride  —  a  binary  salt. 

These  salts  and  acids  may  be  referred  to  the  water-type  by  counting 

in  the  missing  oxygen,  thus  H  Cl  =  hydrogen,  a  neg.  and  the  missing 
0  =  an  acid. 

Write  the  name,  and  mark  as  acid,  base,  or  salt,  the  following: — 

+  - 

Kv  SO+  =  potassium  sulphate  •=.  salt. 

i    

K  CX  —  potassium  cyanide  —  binary  salt. 
Xu_,  r>  —      sodium    sulphide  —  (neither). 

XO-J  —  ammonium  nitrate  —  salt. 

^   nt-A 


28  CHEMICAL   PRIMER. 

H  I  =  ?  Ca  C12  =  Mg  2  CN  —  Mg  CO3  = 

K2  C03  =  K  Br  =  Ba  2  Cl  03  -  (H4N)a  C0a  = 

H4N  HO  =  H3  P04  =  H2  S03  =  Ag  Cl  = 

Mg3  2  P04  =  Mg  2  HO  =  Mg  S04  =  H4  Si  04  = 

NOTE.  — The  third  example  above  teaches  us  that  there  are  many  bina- 
ries which  are  not  to  be  classed  as  acids,  bases,  or  salts.  Only  those 
binaries  containing  the  "salt-forming"  elements  and  radical  linked  in 
Table  No.  1,  are  to  be  thus  classified.  Evidently  there  can  be  no  binary 
bases. 


CHAPTER     XII. 


The  following  Reference  Table  No.  2  will  be  found  a 
great  aid  in  writing  formulas  of  ternaries.  It  is  to  be 
used  in  connection  with  Table  No.  1,  the  negative 
"groupings"  in  No.  2,  being  used  with  the  positive  (to 
H)  elements  in  No.  1,  and  the  positive  groupings  (all  rad- 
icals) of  No.  2,  with  either  the  negative  elements  of  No.  1, 
or  the  negative  groupings  of  No.  2.  The  positive  group- 
ings in  No.  2,  being  radicals,  unite  with  a  single  element 
to  form  a  binary,  while  the  negative  groupings  in  No.  2, 
not  being  radicals  (in  the  same  sense),  unite  with  a  single 
element  to  form  a  ternary, 

EXAMPLE. 

(C2  H6)a  O  =  ethyl  oxiofe  (common  ether)  =  a  binary ; 
but 

Mg  CO3  =  magnesium  carbonate  =  a  ternary;  and 
K  HO  =  potassium  hydrate  =  a  ternary. 


THEORETICAL    CHEMISTRY. 


29 


REFERENCE  TABLE   NO.   2. 


GROUPINGS. 


NEGATIVE. 

HO  =  hydrate. 
NO3  =  nitrate. 
Cl  O3  =  chlorate- 
C,  H3  O2  =  acetate 

{C18H35O2  -  stearate    \ 
C16H3102  =  palnutate  Mm  fats) 
C18H3302  =  oleate       J 

SO4  =  sulphate 
SO3  =  sulphite 
CO3  =  carbonate 
C2O4  =  oxalate 
C4H4O6  =  tartrate 

Cr  O4  =  chromate 
Se  04  =  selenate 

PO4  —  phosphate 
As  O4  =  arsenate 
As  O3  =  arsenite 
Sb  04  —  antimonate 
B  O3  =  borate 

C6H5O7  =  citrate. 


Quadrivalent  (  si  o4  = 

Or  Tetrad.  1    PA  =  pyrophosphate 


POSITIVE. 


(Radicals) 

H4N  —  ammonium 
C,H5  =  ethyl 

C6H5  =  phenyl 
C  H3  =  methyl 
C5HU  =  amyl 


C3H5  =  glyceryl  (in  fats) 


It  has  probably  been  noticed  that  in  the  examples  given  in  the  pre- 
vious chapters,  all  hydrates  contain  HO;  which  acts  as  a  monad  with 
reference  to  the  elements  that  go  with  it,  also,  that  all  sulphates  con- 
tain the  dyad  grouping  S04. 


vA 

•         .    .. 


30  CHEMICAL   PRIMER. 


To  write  the  formula  of  any  substance,  whose  name  is 
given,  as  potassium  carbonate,  we  first  find  the  carbonate 
grouping  in  Table  No.  2,  and  write  it  thus,  C03",  indicat- 
ing for  convenience  its  strength  by  the  two  marks  above. 
In  Table  No.  1  we  find  K  has  a  strength  of  one;  placing 
this  before  the  carbonate  grouping,  we  have  K'CO/.  But 
it  takes  two  monads  to  match  one  dyad,  therefore  we  must 
multiply  K  by  two,  and  we  have  K2C03  for  the  formula 
required. 

Write  the  formula  for  magnesium  phosphate: — 
phosphate  grouping  =  PO/" 
magnesium  ==  Mg"; 

As  it  takes  three  dyads  to  match  two  triad;},  we  have 
Mg3  2  PO4  for  the  required  formula. 

NOTE  1. — The  above  Table  contains  only  the  most  common  groupings. 
There  are  phosphate  groupings  other  than  the  two  mentioned;  also  other 
borate,  sulphate,  and  silicate  groupings,  etc.  For  rarer  groupings  see 
"Table  No.  2,  continued."  The  number  of  radicals,  both  negative  and 
positive,  is  countless.  It  is  well  for  beginners  to  put  a  vinculum  above 
the  groupings  and  radicals  until  they  are  familiar  with  the  method  of 
matching  them. 

NOTE  2. — H,  united  with  the  hydrate  grouping,  gives  HTTO  or  H2O 
=  hydrogen  oxide,  a  binary.  The  grouping  HO  is  often  considered  a 
compound  radical  (hydroxyl)  and  its  compound  with  an  element  is  some- 
times named  as  a  binary.  Ex:  K  HO  =  potassium  hydroxide,  instead 
of  as  in  third  example  above. 


« 


THEORETICAL   CHEMISTRY.  31 


CHAPTER    XIII. 


Write  formulas  for  the  following,  and  mark  as  acid,  6<we,  or  salt: — 

potassium  arsenate  =  K3As  04  —  salt. 

calcium  acetate  =  Ca  2  C2H302  =  salt. 

hydrogen  nitrate  =  H  N03  =  acid. 

magnesium  hydrate  =  Mg  2  HO  =  base, 
hydrogen  silicate  =  barium  phosphate  = 

calcium  oxalate  =  lead  chromate 

sodium  carbonate  =  potassium  arsenate  = 

calcium  phosphate  =  ethyl  hydrate  (common  alcohol)  = 

hydrogen  acet.ite  =  ammonium  oxalate  = 

sodium  hydrate  =  hydrogen  tartrate  = 

lead  carbonate  =  glyceryl  hydrate  (glycerine)  = 

magnesium  phosphate  =  barium  nitrate  — 

hydrogen  citrate  =  silver  arsenite  = 

NOTE.  — Xotice  that  in  negative  groupings  containing  three  or  more 
elements,  the  hydrogen  is  not  counted  in  applying  the  water-type.  See 
calcium  acetate  above. 

As  there  is  in  acids  but  one  element  unknown  (or  vari- 
able), the  acids  are  often  called  by  pet  names,  using  this 
element  as  an  adjective;  thus, 
H  XO3  =  nitric  acid,  instead  of  hydrogen  nitrate. 
H2SO4  =  sulphuric  acid,  instead  of  hydrogen  sulphate. 
H,SO3  =  sulphurous  acid,  instead  of  hydrogen  sulphite. 

In  the  pet  name  of  binary  acids  both  elements  are  used;  as  H  Cl  = 
hydrochloric  acid  (or  chlorohydric),  instead  of  hydrogen  chloride. 
(H  Cl  has  still  another  pet  name  used  in  commerce,  a  commercial  name, 
muriatic  acid. )  As  you  should  not  call  a  stranger  by  his  pet  name,  so 
it  is  much  better  for  you  not  to  call  any  chemical  compound  by  its  pet 
name  till  you  know  its  composition  thoroughly  and  its  chemical  (system- 
atic) name. 

NOTE. — Most  chemical  compounds  have  one  or  more  pet  names,  used 
in  commerce,  by  miners,  by  workmen  in  the  arts,  by  mineralogists,  or 
by  pharmacists.  In  works  on  chemistry  these  names  are  often  inserted 
after  the  chemical  name  (or  vice  versa).  The  druggist  must  learn  at 


32  CHEMICAL  PRIMER. 


\ 


least  three  different  names  for  nearly  all  substances.  For  example,  a 
boy  calls  for  "copperas."  The  druggist  thinks  "iron  sulphate"  and 
takes  it  from  a  bottle  labeled,  in  Latin,  "Ferri  Sulphas."  The  older 
chemists  say  sulphate  of  copper,  of  magnesia,  of  lime,  of  soda,  of  po- 
tassa  (or  potash),  for  respectively,  copper,  magnesium,  calcium,  sodium, 
and  potassium  sulphate. 

If  the  molecular  composition  of  the  acids  has  been  mastered,  they  may 
be  called  by  their  pet  names  hereafter.  Notice  that  the  formulas  for  all 
acids  begin  with  H,  while  formulas  for  all  bases  end  in  the  grouping 
HO. 

Write  formulas  for  the  following: — 

phosphoric  acid  acetic  acid 

chromic  acid  boracic  acid 

citric  acid  pyrophosphoric  acid 

hydrofluoric  acid  sulphurous  acid 

Inspection  of  the  following  questions  will  show  that  the 
methods  of  solution  are  the  same,  whether  the  com- 
pound is  a  binary  or  a  ternary. 

1.  In  580  kgs.  of  the  iron  ore,  ferrous  carbonate  (Fe  C03  spathic  iron), 
how  much  iron?  « 

Fe  =  56  at.  wt.  116  Fe  C03  =  56  Fe 

C  =  12       "  1       "        =  T{-F  of  56  Fe, 

03  =  48       "  580  kgs.       "        =  A|o  of  56  kgs  Fe.  = 


Fe  C03  =  116  mol.  wt.  280  kgs.—  Ans. 

2.  How  much  zinc  sulphate  could  be  made  from  130  kgs.  of  Zn? 

Zn  =  65  65  Zn  =  161  Zn  SOi 

S    =  32  1  Zn  =  ^  of  161  Zn  S04 

04  =  64  130  kgs.  Zn  =  ™-g  of  161  kgs.  Zn  S04  = 

Zn  SO*  =  161  322  kgs.— Ans. 

3.  In  100  kgs.  of  potassium  arsenate  how  mucli  arsenicum  ? 

4.  In  150  gms.  of  mercuric  (Hg  =  dyad)  nitrate,  how  much  mercury? 

5.  In  75  gms.  of  mercurows  (Hg2  —  dyad)  nitrate,  how  much  mer- 
cury? 

6.  How  much  lead  carbonate  (white  lead)  could  be  made  from  50  kgs. 
of  lead? 


REACTIONS. 


33 


CHAPTER    XIV. 


We  have  seen  that  chemical  changes  are  called  reactions. 
There  are  various  classes  of  reactions,  of  which  the  sim- 
pler should  be  thoroughly  mastered  by  beginners,  and  the 
more  complex  let  severely  alone. 

CLASS  1. 
Reaction  by  Direct  Union  (or  Separation). 

EXPERIMENT.  1.— Heat  a  small 
quantity  of  sulphur  well  mixed 
with  fine  copper  filBHg»  on  a 
broken  test-tube  or  other  piece 
of  glass;  a  reaction  takes  place 
and  copper  sulphide  is  formed. 
Reaction  (atomic):  Cu  -f-  S  = 

copper     sulphur 
(red)       (yellow) 

CuS 

copper  sulphide 
(blackf 

EXP.  2.— In  a  test-tube  of 
hard  glass  place  a  small  quan- 
tity of  mercuric  oxidt,  (red)  and 
close  by  rubber  cork  through 
which  prssesafine  glass  tube 
Place  mouth  of  tube  below  the 
The  oxygen  sepa- 


3- 


connected  to  rubber  tubing  (Fig.  3). 

surface  of  water  and  heat  test-tube  to  dull  redness. 

rates  from  the  mercury  and  escapes  bubbling  through  the  water,  while  the 

mercury  condenses  in  a  ring  upon  the  colder  part  of  the  test-tube. 


Reaction: 


HgO 

red  solid 


Hg  + 

liquid        ii 


O 


34  CHEMICAL   PRIMER. 

EXP.  3.  —  Burn  a  small  piece  of  magnesium  ribbon  in  the  air;  the  oxy- 
gen of  the  air  unites  with  the  magnesium,  forming  magnesium  oxide. 

Reaction:     Mg    -f    0    =    Mg  0 

magnesium       oxygen    magnesium  oxide 

1.  How  much  Mg  O  could  be  made  by  burning  30  gms.  of  Mg?  f  -^  ~  '/-/ 

2.  If  you  make  80  gms.  of  Mg  0,  how  much  Mg  must  you  take  ?     -  C  9 

Air  is  composed  of  one  part  by  volume  of  the  gas  oxy- 
gen and  about  four  parts  by  volume  of  the  gas  nitrogen 
(with  traces  of  carbonic  oxide  and  vapor  of  water,  etc.). 
Burning,  or  combustion,  is,  in  general,  the  ra.pid  union 
of  a  substance  with  oxygen.  The  temperature  at  which 
the  substance  takes  fire,  i.  e.,  unites  rapidly  with  the  oxy- 
gen of  the  air,  is  called  the  igniting  point  (i  e.,  kindling 
point).  Of  course,  the  product  of  the  burning  will  be 
an  oxide. 

EXP.  4.  —  Burn  some  sulphur  in  a  bottle  containing  a  small  quantity 
of  water.  (See  Fig.  13  and  Exp.  23.  S  in  burning  always  acts  as  a 
tetrad.) 

Reaction  (a):    8  +  0^=  S02  (a  gas) 

Close  the  mouth  of  the  bottle  and  shake; 

Reaction  (b):    S02  -f-  H,0   =  H2S03  (an  acid) 
Test  for  the  acid  by  litmus  paper. 

EXP.  5.  —  Scrape  some  fine  powder  from  a  piece  of  quicklime  into  a 
test-tube  of  water; 

Reaction:    Ca  0   +    H,0     =    Ca  2  HO  (a  base) 

quicklime  water-slaked  liine, 

a  soft  solid,  part 
of  which  dissolves 

Test  for  the  base  by  litmus  paper. 

The  last  two  reactions  re^7eal  the  fact  that  there  are  different  kinds  of 
oxides. 


The  two  principal  classes  of  oxides  are:  — 

1.  Acid-forming  oxides. 

2.  Basic  oxides. 


*~\        f^yvvx^H  ^       /X4vi^ 


REACTIONS.  35 


The  first  are  oxides  of  negative  elements  and  they  unite 
directly  with  water  to  form  acids,  as  in  reaction  (b)  of 
EXP.  4. 

The  second  are  oxides  of  positive  elements  (metals)  and 
unite  directly  with  water  to  form  bases,  as  in  reaction  of 
EXP.  5. 

Acid-forming  oxides  are  often  called  anhydrides  (without  water), 
since  they  may  be  considered  as  acids  deprived  of  water. 

EXAMPLE. 
S0_,  —  sulphurcw.s  anhydride. 

The  older  chemists  called  the  anhydride  the  acid,  as  S02  =  sulphur- 
ous  acid,  but  this  is  not  now  correct  usage, 

Basic  oxides  are  often  called  bases.  (It  is  important  to  know  that 
this  is  still  correct  usage.  Indeed,  some  authors  give  as  the  definition, 
"A  base  is  a  metallic  oxide,"  and  these  authors  call  the  true  base  a 
"hydrated  oxide"  or  "hydrated  base.")  Basic  oxides  unite  with  acids 
to  form  salts,  just  as  the  true  bases  do,  and  by  a  reaction  very  similar. 

It  will  be  seen  that  the  term  "base"  is  used  by  chemists  somewhat 
indefinitely.  In  a  wide  sense  it  is  used  of  any  substance  that  will  unite 
with  an  acid  to  form  a  salt  (or  a  salt  and  water,  or  a  salt  with  free  hy- 
drogen, etc.).  In  this  wide  sense  it  would  include:— 

1.  Positive  elements  (or  groupings). 

2.  Basic  oxides. 

3.  Positive  hydrates. 

The  word  "base  has  thus  far  been  used  in  this  last  and  restricted 
sense.  The  word  "alkali'  is  also  used  in  a  comprehensive  sense.  The 
sense  of  the  words,  however,  may  easily  be  told  from  the  connection. 


' 


36 


CHEMICAL   PRIMER. 


CHAPTER    XV. 


CLASS  2. 
Reaction  by  Change  of  Partners. 

EXP.  6.— Dissolve  one  gram  of  sodium  chloride  (common  salt)  in  nine 
grams  of  (distilled)  water  (a  ten  per  cent,  solution).  Dissolve  one  gram 
of  silver  nitrate  (lunar  caustic)  in  nineteen  grams  of  water  (a  five  per 
cent,  solution).  Pour  a  little  of  the  first  solution  into  a  small  test-tube, 
and  into  it  let  fall  a  few  drops  taken  from  the  second,  by  means  of  a 
glass  tube  pipette  dipped  beneath  the  solution  and  closed  at  the  opposite 
end  by  the  finger.  A  beautiful,  white,  curdy  solid  (silver  chloride)  is 
formed  by  the  reaction,  and  slowly  settles  to  tile  bottom  of  the  test-tube. 


Fig.  4.    (a) — lead  post,    (b)— rubber  band. 

Taking  this  reaction  as  the  type  of  its  class,  we  may 
learn  much  from  it. 


REACTIONS. 


37 


Just  as  by  change  of  partners, 


(  George  "|  ^  /  Charles  \  ^  (  George  \  •£  /  Charles  | 
{   Lucy   j   •    \  Emma  }         |  Emma  )~\    Lucy   j 


so 


XaCl     +    AgN03     =     NaN03 


i  odium 
chloride 


•ilver 
nitraU 


AgCl 

silver 
chloride 
f       Insoluble 
)    solid,  called 


/  Soluble  solid  ^  f       Insoluble  ) 

\  and  therefore  /  )    solid,  called  I 

J  not     precipi-  I  ~\    a,      precipi-  f 

\  tated,  but  re-  f  «.  t  itc.  ) 

I  maining       in  \ 

\  enlnri.-.u 


NOTE. — This  is  a  very  simple  and  frequent  method  of  reaction.  Fil- 
ter, wash,  and  preserve  all  precipitates  for  future  use  in  experiments,  or 
as  samples  of  the  various  compounds.  (See  EXP.  7.)  Carefully  label  the 
vials  in  which  precipitates  are  preserved.  It  will  be  noticed  that  Ag  Cl 
turns  dark  when  exposed  to  the  light.  (See  SILVER.  ) 

Water  favors  chemical  change. 

(There  are  exceptions. — Water  does  not  favor  ordinary  combustion.) 
Thus,  two  substances  in  solution  will  react  with  each  other,  which 
would  not  if  they  were  mixed  dry.  Iron  rusts  (unites  slowly  with  the 
oxygen  of  the  air,  forming  ferric  oxide  Fe.,03)  if  exposed  to  the  air  wet. 
Knives  and  forks  must  be  wiped  dry,  else  they  rust.  Solution  divides 
a  substance  more  minutely  and  evenly  than  can  be  done  by  any  other 
method  of  mechanical  division.  Solution  separates  the  molecules.  For 
instance,  if  a  teaspoonful  of  common  salt  be  thrown  into  a  barrel  of 
water  and  dissolved,  molecules  of  salt  may  be  found  in  every  drop  of 
the  entire  barrel.  They  seem  to  move  among  the  molecules  of  water 
freely,  the  water  giving  them  an  atmosphere  in  which  they  easily  per- 
form reactions  with  other  substances.  The  water  is  not  written  in  the 
reaction,  unless  it  really  takes  some  part  in  the  atomic  changes. 

When  a  substance  dissolves  in  water,  and  unites  chemically  with  the 
water  to  form  another  compound  (as  in  reactions  of  EXP.  4  and  5),  this 
is  not  a  mere  solution,  but  something  more.  In  a  mere  solution  the  sub- 
stance goes  into  the  water  (somewhat  as  grains  of  sand  might  be  poured 
into  a  measure  of  peas)  without  uniting  with  the  molecules  of  water  at 
all. 

A  gas,  as  we  have  already  learned,  may  be  dissolved  in  water  as  well 

as  a  solid.  „ 

U     ai,  -wAfr  ^  * 


38 


CHEMICAL   PRIMER. 


A  liquid  may  also  be  dissolved  in  water,  but  we  speak  of  the  liquid 
not  as  dissolved  in  water,  but  as  diluted  with  water  (or  mixed)  and  we 
do  not  speak  of  the  resulting  liquid  as  a  solution.  (See  VOLATILE  OILS.  ) 

When  as  much  as  possible  of  the  substance  is  dissolved  in  a  certain 
amount  of  water,  the  solution  is  said  to  be  a  saturated  Solution. 

Many  solids  and  gases  are  insoluble  in  water.  (Some  liquids  will  not 
mix  with  water  and  therefore  cannot  be  diluted  with  water. )  Often 
these  may  be  dissolved  in  other  liquids,  as  alcohol  (ethyl  hydrate),  hy- 
drochloric acid,  etc.  The  liquid  dissolving  the  substance  is  called  a 
solvent. 

Whenever  two  substances,  one  at  least  being  in  solution,  react,  forming 
a  solid  insoluble  in  the  liquid,  the  resulting  solid,  as  it  usually  quickly 
falls  to  the  bottom,  is  appropriately  called  a  precipitate.  If  soluble 
solids  are  formed  at  the  same  time,  they  of  course  remain  in  solution. 
If  gases  are  formed  in  the  reaction,  they  come  off  from  the  liquids  in 
bubbles.  Substances  which  react  with  each  other  as  in  the  above  reac- 
tion, especially  those  that  are  much  used  in  the  chemical  laboratory,  are 
called  reagents. 

EXP.  7. — Into  a  test-tube  containing  silver  nitrate  solution  let  fall  a 
few  drops  of  dilute  hydrochloric  acid.  The  chemicals  react  by  change 
of  partners,  as  in  EXP.  6,  thus: — 

Reaction:    H  Cl     4-     AgN03     =     H  KO3     -J-     Ag  Cl 


hydrogen 
chloride 


silver 
nitrate 


hydrogen 
nitrite 


^g< 

sllvc 


chloride 
(precipitate) 


Precipitates  may  be  separated  from  the  liquid  by  filtration. 
and  fold  some  filter  paper,  thus:  — 


Cut 


Fig.  5. 


and  place  it  on  a  funnel  (tunnel),  pouring  the  contents  of  the  test-tube 
upon  it.  ,    <  '      T, 


V 


LY   ^  to. 


REACTIONS. 


39 


6.— Section  of  Filter  Stand. 


The  precipitate  remains  upon  the  filter,  while  the  liquid  called  fll« 
trate  passes  through.  Wash  the  precipitate,  to  free  it  entirely  from 
the  filtrate,  by  forcing  with  the  breath  water  in  fine  spray  from  wash 
bottles  upon  it.  Remove  the  precipitate  and  dry  upon  glass,  or  dry 
before  removing,  a>  is  sometimes  more  convenient. 


Bottle  for  cold  water. 


HS.  7- 


Flask  for  hot  water. 


; 


40 


CHEMICAL   PRIMER. 


CHAPTER    XVI. 


CLASS  2. — (continued.) 

EXP.  8. — Place  a  very  little  ferrous  sulphide  in  a  small  bottle,  and 
pour  upon  it  dilute  sulphuric  acid.  [In  some  cases  the  reaction  is  n^4- 
prompt.  Tin*  depeiiuo  upon  preparation  of  Fe  S  used.  Heat  acid  and 
Fe  S  in  test-tube,  Fig.  3  and  Fig.  18.] 

/ 
Reaction:    Fe  S    -f     H.2S04     =    Fe  S04     +     H2S 

As  H^S  is  a  gas,  it  comes  off  in  bubbles. 
Close  the  mouth  of  the  flask  by  a  rubber 
cork,  through  which  a  fine  glass  tube 
passes.  By  means  of  a  rubber  tube  and 
another  glass  tube,  allow  the  gas  to  pass 
into  water.  As  the  gas  is  soluble  (three 
volumes  in  one  of  water),  we  have  a  solu- 
tion of  the  gas.  Set  this  aside  carefully 
corked,  as  a  reagent,  (It  decomposes  in 
about  four  weeks  and  becomes  worthless. ) 


Fig.  8.— Making  solution   of 
hydrogen  sulphide. 


Caution. — H2S  is  a  poisonous  gas,  and  EXP.  8  should  be  performed 
under  a  gas  chimney,  or  near  a  window  with  an  outward  draft.  (To 
breathe  a  small  quantity  mixed  with  air  will,  however,  do  no  harm. ) 
This  gas  is  largely  used  in  the  laboratory,  and  chemists  are  often  more 
careless  with  it  than  is  consistent  with  health.  Learn  to  be  cautious  and 
careful  in  performing  all  experiments,  folloiriny  directions  minutely. 

EXP.  9. — To  a  solution  of  lead  acetate  in  test-tube  add  drop  by  drop 
solution  of  H.ZS.  (Reagents  are  hereafter  presumed  to  be  in  solution. ) 


Reaction:    Pb 


lead 

acetate 


+     H.S 

hydrogen 
sulphide 


(bh 


PbS     + 

lead 

sulphide 

ck  precipitate) 


2  H 


hydrogen 
acetate 


It  will  be  noticed  that  when  the  hydrogen  changes  partners  with  the 
lead  atom  and  takes  the  acetate  grouping,  the  hydrogen  and  acetate 
grouping  being  univalent,  they  are  matched  one  to  one,  giving  us  two 


REACTIONS. 


41 


molecules  of  acetic  acid.  It  would  he  incorrect  to  write  H2  2  C2H302. 
Never  put  t>ro  monads  with  two  monads  in  reactions^  but  always  owe 
monad  with  one  monad,  and  if  there  be  two  of  each,  double  the  mol- 
ecule. 


VO   m( 


Just  as  we  must  take  two  Monads  to  match  one  dyad 
in  a  binary,  so  \ve  must  take  two  molecules  containing 
monad  partners  to  react  with  one  molecule  containing 
dyad  partners. 

EXP.  10.  —  To  mercuric  chloride  (corro- 
sive sublimate)  add  drop  by  drop  potas- 
sium iodide.  (Fig.  9  represents  a  conven- 
ient test-tube  stand.  ) 

Reaction:    Hg  C12     +     2KI     = 


potassi 
iodide 


HgI2 

mercuric 

iodide 
(red  precipitate) 


2KC1 

potassium 
chloride 


If  too  little  is  added,  the  precipitate  dis- 
solves; if  too  much  is  added,  the  precipi- 

tate dissolves,  i.  e.,  the  precipitate  dissolves  in  excess  of  either  re- 
agent. Xotice  that  the  molecule  of  mercuric  chloride  contains  dyad 
partners  (Hg  =  a  dyad,  and  C12  two  monads  =  a  dyad,)  while  potas- 
sium iodide  contains  monad  partners;  therefore,  we  must  take  two  mol- 
ecules of  the  latter  to  react  with  one  of  the  former. 

EXP.  11.  —  Into  a  solution  of  arseno?^  oxide  (dissolve  in  hot  water  and 
filter)  let  fall  a  few  drops  of  dilute  hydrochloric  acid. 

Reaction  (a):    As  A     +     6  H  Cl     =     2  As  C13     +     3  H^O 

As203,  a  molecule  containing  hexad  partners,  requires  six  molecules 
of  H  Cl  to  react  with  it.  As  C13,  arsenous  chloride,  being  soluble  in 
water,  does  not  appear  as  a  precipitate.  Into  the  test-tube  drop  solu- 
tion of  H2S. 

Reaction  (b):    2  As  C13  -f  3  H2S   =  As,S3  -f  6  H  Cl 

(lemon  yellow 
precipitate) 

In  reaction  (b)  we  must  take  tu:o  molecules  containing  triad  partners 
(As  C13)  to  react  with  tliree  molecules  containing  dyad  partners  (H2S), 
just  as  we  take  two  triad  elements  to  match  tliree  dyad  elements  in 
forming  binaries.  In  the  second  member  of  the  equation  we  must  be 


1*** 


42  CHEMICAL   PRIMER. 

careful  to  match  the  atoms  according  to  their  "  strength"  and  to  mul- 
tiply the  molecules  afterward,  so  that  the  number  of  atoms  of  any  ele- 
ment shall  be  the  same  in  both  members. 

EXP.  12. — To  lead  acetate  (sugar  of  lead)  add  magne- 
sium sulphate. 

Reaction :  Pb  2C2H  A  +  Mg  SO4  =  Pb  SO4+  Mg  2C2H3O2 

a  poison  its  antidote  insoluble  and          soluble,  but  harm- 

therefore  harmless  less  salt 

(white  precipitate) 

Inspection  of  this  last  reaction  will  reveal  the  exact 
nature  of  a  chemical  antidote.  Let  the  test-tube  repre- 
sent the  stomach.  A  chemical  antidote  is  a  substance 
which  will  unite  with  the  poison,  forming  insoluble  or 
harmless  compounds,  or  both.  (See  ANTIDOTES.) 

EXP.  13. — To  calcium  hydrate  (lime  water)  add  ammonium  carbonate. 
Reaction:    Ca  2  HO  +  (H4N)2CO3  -  Ca,C03  +  2  H4N  HO 

white  precipitate 
(chalk) 

Inspection  of  the  following  questions  and  the  method 
of  solving  them  will  open  to  the  attentive  student  a  wide 
field  for  careful  and  accurate  work.  To  such  a  student 
the  problems  are  not  difficult. 

a 

"""M.  From  542  rrtgs.  of  mercuric  chloride,  how  much  mercuric  iodide 
could  be  made  by  adding  potassium  iodide? 

Reaction:    Hg  C12  +  2  K  I  =  Hg  I,  +  2  K  Cl 
200  200 

71  254 

271  mol.  wt.  454  mol.  wt. 

(will  make) 

271  mgs.  Hg  Cl,  =  454  mgs.  Hg  I2 

1      "          "        =  -giT  of  454  Hg  I2 
542      "          "        =  44f  of  454  mgs.  Hg  I2  ==  908  mgs.—  Ans. 

2.  How  much  mercuric  chloride  will  be  required  to  make  150  gms.  of 
mercuric  iodide  (adding  K  I)  ? 

O-t  i   •  fit,    *4~-t 


REACTIONS.  43 


Reaction:    Hg  C12  -{-  2  K  I  =  Hg  I2  +  2  K  Cl 
200  200 

71  254 

271  454 

would  require 

454  Hg  I2  -  271  Hg  CL, 

1      •«        =  ^  of  271  Hg  C12 
150  gms.     "       =    }|J  of  271  gms.  Hg  Cl,  =  89|||  gms/— .!/-. 

3.  How  much  potassium  iodide  would  be  required  to  make  227  gms. 
ofHgI2?  Ans.   166  gms. 

\   4.  How  much  potassium  chloride  could  be  made  by  using  996  gms.  of 
potassium  iodide?  Ans.  447  gms. 


CHARTER    XVII. 


CLASS  3. 
Reaction  of  Acid  and  Base. 

When  an  acid  and  base  are  united,  the  result  is  a  salt 
and  water.  The  acid  is  said  to  neutralize  the  base  (or 
vice  versa). 

Ex  P.  14. — To  barium  hydrate  add  drop  by  drop  sulphuric  acid. 
Reaction:    Ba  2  HO  -f  H2S04  =  Ba  S04  -f-  2  H2O 

base  acid  salt  water 

(white  precipitate) 

EXP.  15.. — To  oxalic  acid  add  calcium  hydrate. 

Reaction:   H,C,04  -f  Ca  2  HO  =  Ca  C,04  -f  2  H20 

acid  base  salt  water 

(white  precipitate) 

EXP.  16. — To  sodium  hydrate  add  drop  by  drop  acetic  acid,  till  solu- 
tion is  neutral  to  litmus  paper. 

Reaction:    Xa  HO  +  H  C2H30,  =  Na  C2H302  -f  H20 

base  acid  salt  water 


44 


CHEMICAL    PRTMER. 


There  is  no  precipitate,  be- 
cause sodium  acetate  is  soluble 
in  water. 

Filter  to  remove  any  slight 
solid  impurities  and  evaporate 
to  dryness  in  evaporating  dish 
(or  beaker)  over  a  water  bath, 
?'.  e.,  steam  bath.  (See  Fig.  10.) 
Sodium  acetate,  a  solid,  remains. 

NOTE.  —  Whenever  a  water 
bath  is  recommended,  the  simple 
meaning  is  that  the  evaporation 
be  carefully  done,  so  as  not  to 
scorch  or  sublime  the  residue. 
It  may  be 


Fig.  10.— Water  Bath. 

The  water  bath  prevents  the  heat  from  rising  above  100°  C. 
dispensed  with  in  most  cases  if  sufficient  care  be  used. 

CLASS  3  is  only  another  form  of  CLASS  2.  In  reactions  of  CLASS  3  the 
same  law  holds  good,  viz. :  "That  two  molecules  containing  monad  part- 
ners must  be  taken  to  react  with  one  molecule  containing  dyad  partners, 
etc." 

CLASS  4. 
Reactions  of  Acids  and  Carbonates. 

In  these  reactions,  the  carbonate  grouping  breaks  up. 
When  an  acid  unites  with  a  carbonate,  the  result  is  a 
salt,  water,  and  carbonic  oxide  (a  gas).  The  law  in  re- 
gard to  molecules  containing  partners  of  different  strengths 
holds  good,  as  in  the  last  two  cases.  This  reaction  is  fre- 
quently used  by  the  druggist  and  pharmacist. 

EXP.  17. — To  acetic  acid  add  sodium  carbonate  (solid  or  in  solution) 
till  effervescence  ceases.  (Effervescence  is  the  bubbling  caused  by  the 
rapid  separation  of  a  gas  from  a  liquid. ) 

Reaction:    Na2C03  +  2  H  C2H30.  =  2  Na  C2H3O2  -f  H,0  +  C  O2 

carbonate  acid  salt  water          carbonic 

(soluble)  oxide 

Filter,  evaporate  filtrate,  and  preserve.  The  salt  is  obtained  as  in 
EXP.  16.  The  heat  of  evaporation  entirely  expels  any  C  02  that  may  be 
held  in  solution  after  the  reaction. 


REACTIONS.  45 

Ex  P.  IS.  -Into  dilute  citric  acid  let  fall  an  excess  of  finely  pulverized 
calcium  carbonate  (marble).  When  effervescence  ceases,  boil  (to  pre- 
cipitate any  dissolved  carbonate),  filter,  evaporate,  and  preserve  as  before. 

Reaction:   3  Ca  COS  +  2  H3CeH507  =  Ca3  2  C6H507  +  3  H,0  +  3  CO, 

carbonate  acid  salt  water  carbonic 

oxide 

NOTE.  —  Three  molecules  containing  dyad  partners  (Ca"C03")  must 
react  with  two  molecules  containing  triad  partners  (HVCfrEsOy'"),  as 
before.  (See  also  EXP.  33. ) 

Notice,  in  evaporating,  that  this  salt  (calcium  citrate) 
is  less  so  uble  in  hot  than  in  cold  water;  an  exception  to 
the  general  rule,  that  "for  equal  volumes,  hot  water  dis- 
solves more,  of  a  solid  than  cold  water. 

As  a  rule,  "hot  water  dissolves  less  of  a  gas  than  an 
equal  volume  of  cold  water."  Indeed,  many  gases  not 
only  will  not  dissolve  at  all  in  boiling  water,  but  may  be 
completely  expelled  from  water,  in  which  they  may  have 
been  previously  dissolved,  by  boiling  it. 

Before  leaving  these  chapters  on  reactions,  the  student  should  be  able 
to  write  promptly  any  reaction  belonging  to  either  of  the  four  classes, 
provided  he  has  the  names  of  the  two  substances  given  and  the  two  refer- 
ence tibies  before  him. 

MISCELLANEOUS   PROBLEMS. 

I.  Write  formulas  for  five  binary  acids. 
•2.   Write  formulas  for  ten  ternary  salts. 

3.  Write  formulas  for  two  binary  salts. 

4.  Write  formulas  for  six  ternary  acids. 

5.  Write  formulas  for  five  bases. 

^6.  In  L">0  gms.  of  arsenous  oxide,  how  much  As? 

7.  Iri  1000  gms.  of  silver  chloride,  IIOAV  much  silver? 

8.  How  much  mercuric  sulphide  could  be  made  by  using  50  kgs.  of 
mercury  (Hg")? 

9.  Reaction  when  phosphorus  burns  in  air? 

10.  When  carbon  burns? 

Reactions  when  the  following  are  united: — 

II.  Stannous  chloride  (Sn")  and  hydrogen  sulphide? 

12.  Copper  sulphate  and  sodium  hydrate?  , 


^        &•'  *J~*^>        s*-*    1*****    '' 


46 


CHEMICAL   PRIMER. 


13.  Sodium  carbonate  and  hydrochloric  acid? 

14.  Ammonium  carbonate  and  calcium  hydrate? 

15.  Potassium  hydrate  and  sulphuric  acid? 

16.  Calcium  hydrate  and  citric  acid? 

17.  Potassium  carbonate-  and  tartaric  acid? 

18.  Acetic  acid  and  magnesium  carbonate? 

19.  To  make  190  gms.  of  magnesium  chloride  (by  adding  H  Cl),  how 
much  magnesium  carbonate  must  be  taken  ? 

20.  How  much  arsenous  oxide,  As-j03  (white  arsenic)  was  contained 
in  a  vessel  full  of  water,  from  which  15  mgs.  of  arsenous  sulphide  was 
precipitated  (by  adding  H  Cl  and  H2S)? 


CHAPTBR    XVIII. 


OXYGEN. 

EXP.  19. — Carefully  pulverize  in  a  mortar  a  small  quantity  of  potas- 
sium chlorate,  and,  having  mixed  it  thoroughly  with  an  equal  bulk  of 
pure  manganese  dioxide,  introduce  into  a  small  copper  retort.  Heat  by 
a  strong  alcohol  flame,  or  flame  from  a  Bunsen's  burner.  Collect  0  in 
receivers  over  a  pneumatic  tub,  as  represented  in  Fig.  11.  [A  glass 
flask  heated  upon  a  sand  bath  (iron  basin  filled  with  sand,  Fig.  21)  may 
be  used  in  place  of  the  copper  retort.  ] 

Reaction:    K  Cl  O3   —   K  Cl   -f    03 


Fig.  11. 
(a)— retort  stand;  (b)— retort;  (c) — receiver;  (d)  -pneumatic  tub;  (ej— receiver  removed. 


OXYGEN.  47 


NOTE. — The  presence  of  Mn  O2  causes  the  0  .to  come  off  more  steadily 
and  at  a  lower  temperature,  but  as  it  takes  no  part  in  the  reaction,  (?)  it  is 
not  written.  The  first  bubbles  that  come  off  are  composed  principally 
of  i  air  from  the  retort  and  should  be  allowed  to  escape.  The 
O  often  looks  cloudy,  because  small  particles  of  the  salt  and  oxide  are 
carried  over  by  the  draft.  These  gradually  dissolve  or  settle  into  the 
water.  Three  or  four  receivers  should  be  inverted,  and  as  fast  as  filled 
removed  by  means  of  a  small,  shoal  tin  cover,  holding  a  little  water,  to 
prevent  the  escape  of  the  gas.  Small  quantities  of  0  may  be  conven- 
iently made  by  using  test-tubes  as  retorts,  test-tubes,  or  bottles,  as 
receivers,  and  a  beaker  or  basin  as  a  pneumatic  tub.  (See  Fig.  3.) 
Avoid  heating  too  rapidly  in  one  place,  by  carrying  lamp  or  burner  back 
and  forth  slowly,  so  that  test-tube  shall  pass  through  the  bottom  of  the 
flame,  nearly  touching  the  wick  or  burner. 

Caution. — K  Cl  03  must  not  be  heated  alone.  Commercial  Mn  O.,  is 
sometimes  adulterated  with  carbon  (pounded  coal)  and  when  mixed 
with  K  Cl  03  and  heated,  the  mixture  explodes  violently.  Test  by 
heating  in  test-tube  a  small  quantity  of  the  oxide  and  chlorate  mixed, 
unless  the  former  is  warranted  to  be  pure.  The  delivery  tube  must  be 
removed  from  the  water  before  the  heat  is  taken  from  the  retort,  other- 
wise, as  the  gas  in  the  retort  cools  and  contracts,  the  water  is  forced 
back  along  the  tube  by  atmospheric  pressure.  The  first  that  falls  into 
the  highly  heated  retort  is  instantly  converted  into  steam,  causing  an 
explosion.  Ordinary  care  will  prevent  any  serious  accident.  The  chief 
danger  in  breaking  glass  retorts  is  to  the  eyes. 

Learn  here  that  an  explosion  is  (generally)  caused  by  the  sudden  con- 
version of  matter  from  the  solid  or  liquid  to  the  gaseous  state. 

Oxygen  is  a  colorless  gas,  without  odor  or  taste.  As 
we  have  inferred  from  the  formulas  thus  far  used,  it  is  a 
very  abundant  element.  It  exists  free  (uncombined)  in 
the  air,  forming  one-fifth  its  volume.  Chemically  com- 
bined with  other  elements,  it  forms  by  weight  eight-ninths 
of  water,  one-half  of  minerals,  three-fourths  of  animal 
tissues,  and  four-fifths  of  vegetable  tissues;  in  short,  so 
far  as  we  know,  about  two-thirds  of  the  earth. 

EXP.  20. — Into  a  receiver  (bottle)  of  0,  plunge  a  taper  having  a  live 
coal  upon  the  end,  it  immediately  bursts  into  a  blaze.  Quickly  remove 
ami  blow  out  the  flame.  Repeat  the  relighting  from  twenty  to  forty 


48 


CHEMICAL    PRIMER. 


V   » 

<S 


vi 

4 

4- 

4 


H 

-  "* 


times,  as  may  easily  be  done  before  the  gas  is  exhausted.     Do  not  plunge 
deeper  than  is  necessary  to  rekindle,  as  this  uses  up  the  0  rapidly. 

Wood,  oil,  tallow,  etc.  (things  that  we  ordinarily  burn), 
are  composed  principally  of  H  arid  C,  and  are  therefore 
called  hydrocarbons.  When  hydrocarbons  (as  the  taper 
in  the  experiment)  burn,  two  reactions  take  place,  viz.  :  — 

H,  +  O  =  H2O    (steam))    Gaseous  prod- 

\-ucts     of     the 
C    -f  O2  =  CO2   (a  gas)  J  combustion. 

Immediately  after  the  0  is  exhausted,  pour  into  the  receiver  a  very 
small  quantity  of  water,  and  closing  its  mouth,  shake  at  intervals.  The 
C  02  gradually  dissolves. 

Reaction:    C  O2  -j-  H20  =  H.,C03 

acid  forming  acid 

oxide 

Test  by  litmus  paper,  but  as  H2C03  is  a  very  weak  acid,  litmus  paper 
must  remain  a  little  time  in  it. 

O  is  a  vigorous  supporter  of  combustion.  O  is  heav- 
ier than  air,  for  we  hold  the  mouth  of  the  receiver 
upward  to  retain  the  gas. 

Water  is  the  standard  of  specific  gravity  for  solids  and 
liquids,  and  air  for  gases  (in  physics).  Sp.  gr.  of  air  is  1, 
of  O  1.1+.  But  in  chemistry,  hydrogen  (which  see)  is 
made  the  standard  for  gases. 

EXP.  21.  —Straighten  a  narrow  steel(Fe)  watch-spring 
and  file  the  end  bright.  Attach  (Fig.  12)  a  very  short 
piece  (head)  of  a  common  match,  as  kindling  for  the 
steel.  Ignite  by  flame  and  quickly  plunge  into  a 
receiver  of  O.  The  steel  burns  vividly 


Reaction: 


-f-     04 


=     Fes04 

(triferric  tetroxide 
black  or 


magnetic 
iron  ox.de) 


If  a  large  receiver  is  used,  end  the  head  of  the 
match  is  attached  to  the  spring  by  winding  a  very 
fine  iron  wire  closely  about  both,  the  experiment  is  a 
very  brilliant  one.  This  reaction  is  an  irregular  one, 
that  is,  the  strength  of  iron  is  apparently  not  accord- 
ing to  the  Table.  This  oxide  is  often  called  ferroso- 
.  ferric  oxide,  and  is  supposed  to  be  formed  by  the 
direct  molecular  union  of  the  other  two  (Fe./)a  -{-  ke  0  —  Fe304),  these 
being  formed  also  in  minute  quantities  by  the  reaction. 


tff  f~ 


OXYGEN. 


49 


If  the  air  were  pure  O',  our  iron  stoves  would  take 
fire,  and  a  general  conflagration  would  spread  over  the 
earth.  We  could  not,  for  any  length  of  time,  breathe 
pure  O,  as  it  would  over  stimulate  the  vital  processes.  It 
is  diluted  with  four  times  its  volume  of  the  inactive  gas, 
nitrogen,  forming  the  proper  mixture  to  be  respired.  (See 
pages  34,  58,  and  67.) 

EXP.  22. — Charcoal  bark,  a  small  part  of  which  has  been  heated  to  a 
live  coal,  plunged  into  0  (by  means  of  a  Cu  wire  twisted  about  it), 
bursts  into  a  vivid  combustion. 


EXP.  23.  —  Repeat  EXP.  4  in  jar  of  0.  (Place 
S  on  chalk  in  a  combustion  spoon.  Copper  wire 
twisted  about  a  piece  of  chalk  makes  a  good  com- 
bustion spoon.  ) 

EXP.  24.  —  Cut  under  water,  quickly  and  care- 
fully dry  between  pieces  of  blotting-paper,  a 
small  piece  of  phosphorus  (not  larger  than  a  grain 
of  wheat).  Place  in  a  combustion  spoon,  ignite 
by  hot  wire,  while  lowering  into  a  large  jar  of  0, 
containing  at  the  bottom  a  little  water.  A 
blinding  light  is  caused  by  the  combustion. 


Reaction: 


05    =    P.,05 

dense  white 
fume* 


-,-,.       -o 
Fig.  13. 

In  a  short  time  these  fumes  are  dissolved  in  the  water,  and  the  follow- 
ing reaction  slowly  takes  place:  — 

P,05    +    3H.O    =    2H3P04 

acid  forming 
oxide 

Test  by  litmus  paper. 

Caution.  —  Handle  P  with  great  care,  on  no  account  touching  it. 
The  heat  of  the  hand  may  inflame  it,  and  its  burns  are  dangerous.  Its 
vapor  i.i  highly  poisonous  and  must  not  be  inhaled.  The  dense,  white 
fumes  should  be  immediately  shut  in  by  stopple  attached  to  combustion 
spoon.  (See  Fig.  13.) 

O  is  an  exceedingly  active  gas.  It  alone  supports  all 
ordinary  burning  that  takes  place  in  the  air.  To  bring 
this  gas  in  contact  with  the  blood  is  the  object  of  respiration 

>U^-  o  ^,.  .-  <> 

^ 


50 


CHEMICAL   PRIMER. 


in  animals.  The  blood  absorbs  and  carries  O  to  all  the 
tissues,  the  most  prominent  chemical  change  taking  place 
in  the  body  being  that  of  oxidation.  (See  carbonic 
oxide.) 

There  is  a  peculiar  form  of  condensed  O,  called  Ozone. 
It  is  O  in  an  aUotropic  state.  It  may  be  made  in  various 
ways,  especially  by  the  action  of  electricity  on  common 
O.  It  occurs  in  minute  quantities  in  the  air.  It  is  even 
more  active  than  O  and  is  a  powerful  disinfectant. 

In  ozone  tainted  meat  rapidly  loses  its  putrescent  odor,  because  the 
foul  material  is  oxidized,  forming  relatively  wholesome  compounds.  The 
molecule  of  ozone  may  be  represented  thus  ^  I  with  three  atoms, 
that  of  oxygen  being  |  oo  [  composed  of  two  atoms,  that  is,  three  vol- 
umes of  oxygen  if  it  could  all  be  changed  to  ozone  would  make  but  two 
volumes  of  ozone. 


ciriAf*T 


XIX. 


HYDROGEN. 

EXP.  23. — Place  in  a  small  flask,  or  large  test-tube  (hydrogen  gener- 
ator), some  granulated  Zn.  Upon  it  pour  dilute  (10  per  cent.)  sulphuric 
acid.  Close  mouth  of  flask  with  perforated  rubber  cork,  through  which 
passes  a  fine  glass  tube.  Collect  H  over  pneumatic  tub,  as  in  Fig.  14. 


Zn 


H2S  04     = 


Fig.  14.— Making  Hydrogen. 
A/J-   ^ 


ZnS04     -f     II, 

NOTE.  —  Collect  several  re- 
ceivers of  the  gas,  and,  after 
the  reaction  has  ceased,  filter 
the  liquid  remaining  in  the 
flask;  evaporate  filtrate,  and 
the  white  salt,  zinc  sulphate,  is 
obtained.  If  a.  drop  of  the  fil- 
trate is  placed  on  a  piece  of 
glass  and  set  aside,  away  from 
the  dnxt,  beautiful  crystals  of 
the  salt  are  left  upon  the  glass. 


i         •  <  •  bJ^ 


4~- 


HYDROGEN.  51 


Hydrogen  is  a  colorless  gas,  without  odor  or  taste 
(when  pure).  It  is  the  essential  constituent,  as  we  have  * 
seen,  in  acids.  Indeed,  acids  have  sometimes  been  denned 
as  "salts  of  hydrogen."  H  does  not  occur  free.  It  has 
been  condensed  by  cold  and  pressure,  first,  to  a  liquid  and 
then  to  a  white  solid.  H  is  not  poisonous,  but  destroys 
life,  just  as  water  does,  by  shutting  out  the  O.  The  lungs 
may  be  inflated  with  the  pure  gas  without  harm. 

Caution.  —  Gases  made  by  beginners  must  never  be 
breathed.  As  a  rule,  a  gas  is  obtained  absolutely  pure 
writh  great  difficulty.  For  methods  of  obtaining  gases 
pure,  see  larger  text-books  or  some  treatise. 

EXP.  26.  —  Remove  a  jar  of  H,  holding  the  mouth  downward,  and 
into  it  plunge  slender  lighted  taper.  The  H  takes  fire  and  burns  at  the 
mouth  of  jar,  but  the  taper  is  extinguished  in  the  gas  above.  It  may 
be  relighted  by  the  burning  H  as  it  is  being  removed. 

H  is  lighter  than  air,  for  we  hold  the  gas  by  keeping 
the  mouth  of  the  receiver  downward.  H  is  very  inflam- 
mable, i.  e.,  its  igniting  point  is  low.  It  does  not  sup- 
port combustion  of  hydrocarbons). 

NOTE.  —  Combustible  bodies  and  supporters  of  combustion  are  relative 
terms.  A  jet  of  O  would  burn  in  a  jar  of  H  just  as  well  as  a  jet  of  H 
in  a  jar  of  0.  One  as  well  as  the  other  could  be  called  the  supporter 
of  the  combustion. 

EXP.  27.  —  Collect  H  from  generator  in  test-tube  by  displacement  of 
air.  Pour  upward  into  another  test-tube,  displacing  the  air.  Test  by 
igniting. 

EXP.  '28.  —  Attach  by  rubber  tube  a  clay  pipe  to  generator  and  blow 
soap  bubbles  with  H.  They  ascend  and  may  be  ignited  in  the  air. 

Hydrogen  is  the  lightest  substance  known,  being  about 
1  4  1  times  lighter  than  air.  Chemists  take  hydrogen  as  the 
standard  of  specific  gravity  for  gases.  With  this  stand- 
ard, "one-half  its  molecular  weight  is  the  specific  gravity 
<>f  any  gas."  '?cc  Miscellaneous  Questions,  Chap.  XXII, 
NOTE.)  ^t.  JV  Lj^j^t-  t*  1*4*  < 

OL    M^  *T>—   (v^^^r   ^v^At^jt^  -  °-*4. 


52 


CHEMICAL   PRIMER. 


EXP.  29.—  Fit  a  perforated  cork,  through 
which  passes  a  glass  tube,  deeply  into  a  new, 
dry  porous  cup  (such  as  is  used  in  Bunsen's 
battery).  Melt  over  the  surface  of  the  cork 
sufficient  paraffine  (or  tallow)  to  make  it  air- 
tight. Place  the  end  of  tube  just  beneath 
water  in  a  beaker  (Fig.  15),  and  cover  the 
porous  cup  with  receiver  of  H.  The  H  passes 
by  diffusion  in  through  the  pores  of  the  cup 
much  more  rapidly  than  the  air  passes  out, 
therefore  bubbles  of  air  are  forced  out  through 
the  water.  Remove  receiver  and  soon  the 
water  rises  in  the  tube  because  of  the  diffusion 
__  of  the  H  outward. 

SSSaSKJBSSSSS! 

All  gases  possess  power  of  diffu- 

sion, but  the  power  is  possessed  by  H  in  an  extreme  de- 
gree. The  diftusibility  of  gases  is  "inversely  as  the 
square  roots  of  their  densities,  "($he  density  (or  sp.  gr.)  of 
any  gas  being,  as  given  above,  half  its  molecular  weigh  t.^2fx 


EXAMPLE. 


4  1 

diffusibili'y     •     diffusibility 

of  H  •  of  O 


That  is,  H  has  four  times  the  diffusive  power  of  O,  or  dif- 
fuses four  times  as  rapidly.  H  may  leak  through  vessels 
that  would  retain  O  permanently. 


EXP.  30. — Close  generating  flask  by  a  rub- 
ber stopple,  through  which  passes  a  hard  glass 
tube,  with  fine  opening.  After  the  air  has  been 
expelled  by  the  H,  ignite  the  jet.  The  appa- 
ratus is  the  "Philosopher's  Lamp, 
flame  invert  a  cold,  dry  test-tube, 
dewed  with  moisture. 


Over  the 
It  is  be- 


H 


H20 


' 


When   H   burns,  the   product  is 

Fig.  16.—  Philosopher's  lamp,   water  (steam).      The  II  llaine  gives 
little  light,  but  great  heat.     The  alcohol  (ethyl  hydrate) 

"fl 
< 


HYDROGEN.  53 

flame  gives  little  light  and  great  heat,  because  alcohol 
contains  much  H. 

The  flame  of  the  oxy-hydrogeu  blowpipe  melts  many  substances 
(as  platinum),  infusible  in  ordinary  fire,  the  alcohol  flame,  or  the  flame 
from  a  Bunsen's  burner. 


Fig.  17.— Section  of  ox y -hydrogen  blowpipe. 

The  H  from  the  gasholder  is  first  turned  on  and  ignited,  and  after- 
ward the  0  is  turned  on. 

EXP.  31. — Fill  over  a  pneumatic  tub  a  stout  quart  fruit  jar  one-third 
•with  0,  and  the  remainder  with  H.  Wrap  about  it  a  cloth;  remove,  and, 
holding  the  mouth  downward,  quickly  ignite  by  means  of  a  taper.  A 
sharp  explosion  ensues. 

There  are  two  reports  heard  as  one,  the  second  so  closely  follows  the 
first.  The  first  is  caused  by  the  sudden  (but  not  greater  than  a  few 
volumes)  expansion  of  the  gases  heated  by  their  union;  the  second  is 
caused  by  (the  steam  suddenly  condensing)  the  rush  of  the  air  from  all 
sides  to  fill  the  partial  vacuum.  Caution. — Of  course,  H  explodes 
when  mixed  with  air.  Care  must  be  taken  to  expel  all  air  from  appa- 
ratus before  igniting  jets  of  H.  Never  ignite  large  quantities  of  the 
gas. 

EXP.  32. — Repeat  the  experiment  of  decomposing  water  as  explained 
in  connection  with  Fig.  1. 

This  proves  by  Analysis  the  composition  of  water.  If  we  explode 
two  volumes  of  H  with  one  of  0  and  find  we  have  nothing  but  water  left, 
we  prove  the  composition  of  water  by  Synthesis. 

Water  H.O 
The  wonderful  power  of  chemical  affinity  is  shown  in 


54 


CHEMICAL   PRIMER. 


this  compound.  A  union  of  the  most  inflammable  sub- 
stance known  with  the  most  vigorous  supporter  of  com- 
bustion, forms  another  substance  which  will  extinguish 
fires.  We  have  called  this  substance  by  its  pet  name, 
because  it  is  so  common  a  substance  and  so  generally  dis- 
tributed. Its  systematic  name  (hydrogen  oxide)  is  seldom 
used.  We  have  already  learned  that  water  is  the  general 
solvent  in  nature,  dissolving  most  gases  and  solids  and 
diluting  most  liquids. 

Hard  water  contains  minerals  in  solution;  soft  water 
does  not. 

NOTE. — In  a  narrower,  but  very  common  uoage,  only  such  water  is 
called  hard  as  contains  in  solution  minerals  that  either  react  with  soap,  or 
hinder  its  solution  (see  SOAP).  Water  containing  such  minerals  as  borax 
and  potassium  carbonate  would  be  called  in  the  laundry  soft  water. 
Water  or  soil  containing  potassium  carbonate,  sodium  carbonate,  etc., 
is  often  said  to  be  "alkaline,"  because  these  salts  have  an  alkaline  reac- 
tion upon  litmus,  and  because  the  old  chemists  called  the  strongly  posi- 
tive carbonates  "mild  alkalies."  (They  called  the  strongly  positive 
hydrates  "caustic  alkalies,"  and  these  hydrates  are  still  frequently  thus 
called.) 


EXP.  33.— In  a  test-tube  place  small 
pieces  of  marble  and  cover  with  dilute 
hydrochloric  acid  (ten  per  cent). 

Reaction  (Class  4th):— 
Ca  C03  -f  2  H  Cl  =  Ca  Cl2-f  H20  +  C02 

By  means  of  a  delivery  tube  (Fig.  18) 
pass  the  gas  through  clear  lime  water 
(solution  of  Ca  2  HO,  see  EXP.  5)  in  a 
second  test-tube.  The  lime  water  at 
first  becomes  milky  because  of  white 
precipitate  of  Ca  C03. 


Fig.  18. 


Reaction:    Ca  2  HO  -f-  C02  =  CaC03  +  H20 

base  aci  I  forming  salt 

oxide 

/K*<,  * 


sj- 
ff 


.^_^ 


HYDROGEN.  55 


Allow  the  gas  to  continue  bubbling  through  the  lime  water.      After 
all  the  Ca  is  thrown  down  as  a  carbonate,  the  CO,  dissolves  in  the  watersv  ,7  .^ 

<',,rhonates  dissolve  in  water  containing  CO2  in  solution,  but  not  in  Pur^^\/^^  ^f 

fer.  )      The  water  becomes  clear  again  because  the  calcium  carbonate        T  ,  ^ 

is  dissolved.      This  clear  water  is  now  water  of  "temporary  hardness."  °* 

Boil.      The  C02  in  solution  is  driven  off,  and  the  calcium  carbonate  is 
again  precipitated,  being  insoluble  in  pure  water. 

Hardness  produced  by  earthy  (Ca.  Mg.  Sr.  Ba.,  etc.) 
carbonates  is  called  "temporary  hardness,"  because  the 
carbonate  may  be  precipitated  by  boiling,  leaving  the 
water  soft.  The  "fur"  upon  the  tea-kettle  is  a  precipi- 
tated carbonate. 

Hardness  produced  by  earthy  sulphates  is  called  "per- 
manent  hardness,"  because  the  water  cannot  be  made 
soft  by  boiling.  (See  SOAP.) 

The  vapor  of  water  in  the  atmosphere  is  essen- 
tial, not  only  to  plant  life,  but  to  animal  life  as  well. 
The  earth  would  be  a  vast  desert  were  it  not  that  tons  of 
water  are  constantly  being  carried  up  from  the  ocean  by 
evaporation,  so  that  the  air  currents  may  distribute  it, 
not  alone  to  fall  as  rain,  but  also  to  keep  the  atmosphere 
everywhere  moist. 

Many  substances,  when  they  crystallize  (assume  a  sym- 
metrical shape  in  solidifying),  take  up  a  definite  amount 
of  water,  called  water  of  crystallization.  This  may  be 
expelled  by  heat,  but  the  essential  properties  of  the  sub- 
stance are  not  changed. 

EXP.  34.— Heat  in  a  narrow,  deep  test-tube  of  hard  glass,  small  crys- 
tals of  pure  copper  sulphate  previously  carefully  weighed;  the  water  of 
crystallization  is  expelled  and  part  of  it  condenses  in  small  drops  on 
the  cooler  part  of  the  test-tube.  The  blue  color  disappears.  Wipe 
with  dry  cloth  the  water  from  the  test-tube.  Remove  and  weigh  the 
sulphate.  It  has  lost  over  one-third  its  weight,  as  the  formula  of  cry* 
tallacd  copper  sulphate  is  Cu  S  04,  5  H20.  Touch  with  a  drop  of  water, 
the  color  slowly  returns.  Dissolve  in  a  small  quantity  of  water,  evap- 

Jt^-       tr  &e         .+  £-4. 


56  CHEMICAL   PRIMER. 

orate  slightly,  and  set  aside  to  cool.  Beautiful  crystals  of  copper  sul- 
phate form  as  the  solution  cools. 

Fine  crystals  of  various  substances  may  be  formed  in  this  way,  viz. , 
by  making  saturated  solution  of  the  substance  (slightly  evaporating), and 
setting  aside  for  a  few  days.  Making  a  collection  of  crystals  will  be 
found  a  very  profitable  exercise. 

"Water  of  crystallization  is  not  written  in  ordinary  reactions  of 
substances  in  solution,  but  must  be  taken  into  account  in  dealing  with 
the  dry  solids.  Of  course  a  larger  quantity  of  the  crystallized  solid 
must  be  taken  to  equal  a  smaller  quantity  of  the  uncrystallized,  if  t/te 
solid  takes  up  water  of  crystallization. 

Some  substances,  such  as  sodium  acetate  (Na  C2H3O2 
3  H.O),  sodium  carbonate  (Na2  C  Os,  10  H.2O),etc.,  when 
exposed  to  the  air  lose  their  water  of  crystallization,  and 
crumble  to  powder.  These  are  said  to  be  efflorescent. 

Some  substances,  as  potassium  carbonate  (K2  C  O3), 
when  exposed  to  the  air,  absorb  moisture  and  dissolve 
(or  partially  dissolve).  These  are  said  to  be  deliquescent. 

The  law  of  physics,  that  "heat  expands  and  cold  con- 
tracts," does  not  hold  with  water  in  cooling  from  about 
4°  (C)  to  0°,  through  which  space  it  steadily  expands,  until 
it  freezes  (crystallizes)  at  0°.  At  the  moment  of  freezing 
there  is  a  sudden  and  great  expansion.  (See  Plot  b, 
Fig.  19.)  The  importance  of  this  exception  cannot  be 
overestimated,  for  it  makes  ice  lighter  than  water,  and 
so  prevents  lakes  and  rivers  from  freezing  solid. 

Water  containing  impurities  in  solution  may  be  puri- 
fied by  distillation.  The  water  is  placed  in  a  retort,  or 
"  still,"  is  heated,  rises  as  steam  (at  100°),  which,  passing 
through  the  condenser  (supplied  with  cold  water  in 
direction  of  arrows,  Fig.  19),  condenses,  and  is  collected 
in  a  receiver.  Steam  ("dry  steam")  is  an  invisible  gas. 
That  which  is  seen  and  often  miscalled  steam  is  steam 
condensed  (or  partially  condensed)  into  minute  globules 


NITROGEN. 


57 


of  water  and  held  in  suspension  (like  dust)  by  the  air  (or 
by  the  invisible  steam,  in  which  ease  the  steam  is  called 
"wet  steam.") 


Fig.    19.— Retort,  or  "  still,"  and  condenser.     Plot  b— Effect  of  "cold"  upon  water. 


CHAPTER    XX. 


NITROGEN. 

EXP.  35. — Place  a  piece  of  chalk  on  a  tripod  wire- holder,  standing  in 
a  deep  plate  of  water.  Upon  the  chalk  place  a  small  piece  of  P.  Ignite 
by  hot  wire  and  quickly  invert  a  receiver  over  it.  (Caution,  EXP.  24.) 

p,   +   o,  =   PA 

soluble 
white 
fumes 

The  P  unites  with  the  0  in  the  jar. 
The  phosphoric  oxide  dissolves  and  the 
water  rises  by  atmospheric  pressure  and 
fills  one-fifth  of  the  receiver,  the  space 
before  occupied  by  the  0.  N  remains 
in  the  receiver  above  the  water,  neither 
burning  nor  supporting  the  combustion 
of  the  remaining  phosphorus.  (See 
Phosphorus.) 


Fig.  20. 


58  CHEMICAL   PRIMER. 


Nitrogen  is  a  colorless  gas,  without  odor  or  taste.  It 
forms  by  volume  i  of  the  atmosphere.  N  is  not  poison- 
ous, and  destroys  life  only  by  shutting  out  O.  It  is  not 
inflammable  and  it  does  not  support  combustion.  It  is 
a  very  inert  element.  It  dilutes  the  active  O  of  the  air, 
and  the  mechanical  mixture  is  thus  fitted  for  respiration. 
Some  of  its  compounds  are  by  no  means  inert.  For  ex- 
ample, "nitro-glycerine,"  the  violent  explosive,  is  glyc- 
eryl  nitrate,  and  the  deadly  poison,  prussic  acid,  is  hy- 
drogen cyanide.  No  one  can  predict  with  certainty  the 
character  of  a  chemical  compound  from  the  nature  of  its 
constituents. 

It  might  be  supposed  that,  N  being  lighter  than  O,  the 
air  would  separate  into  two  layers,  the  heavier,  O,  sinking. 
The  two  gases,  however,  are  kept  thoroughly  mixed  by 
the  law  of  diffusion  of  gases. 

N2  O',  hyponitrous  oxide  (acid-forming  ?)' 

N  0,  nitrogen  dioxide  (called  so  because  formula  was  thought  to  be 
N,  O.J. 

N.,  03,  nitrous  oxide  (acid-forming). 

N.,  O4,  nitrogen  tetroxide  (or  peroxide,  at  high  temperatures,  N  0^,). 

N2  O5,  nitric  oxide  (acid-forming). 

These  oxides  illustrate  well  the  great  law  of  multiple 
proportions.  When  one  substance  unites  chemically  with 
another,  it  is  in  some  definite  proportion,  or  multiple  of 
that  proportion.  Whenever  substances  are  united  phys- 
ically (mechanically,  as  in  alloys  of  metals,  etc.)  they 
may  be  united  (mixed)  in  any  proport  on. 

NOTE.— There  is  a  third  class  of  indifferent  oxides,  as  N  0,  neither 
acid-forming  nor  basic.  The  pupil  need  not  give  any  attention,  however, 
to  this  class.  All  the  positive  indifferent  oxides,  as  Mn  0.2,  Ba  Oi}  K.2 
04,  Pb  02,  having  more  0  than  the  basic,  are  called  peroxides.  There 
are  still  other  oxides  which  belong  not  strictly  to  either  of  the  three 
classes,  but  form  acids  or  bases  irregularly  by  decomposition,  as  N2  04  and 
Fe3  04.  For  preparation  of  N2  03  and  N2  05  see  larger  text-books. 


1 


NITROGEN.  59 


Ex  P.  36.  —  Heat  in  flask  ammonium  nitrate  and  collect  gas  over  pneu- 
matic tub  of  warm  water. 

/ 
H4X  X03     -     2  H20     +     X20 

Hyponitrous  oxide  ("nitrous  oxide"  "laughing  gas"), 
inhaled  with  a  small  proportion  of  O,  produces  a  peculiar 
intoxication,  hence  its  name  of  "laughing  gas."  If  the 
pure  gas  is  inhaled,  it  soon  produces  insensibility.  It  is 
much  used  as  an  anaesthetic  by  dentists  and  by  surgeons 
in  minor  operations.  It  is  kept  condensed  in  liquid  state 
in  iron  cylinders.  (See  Caution,  under  Hydrogen,  Exp. 
25.) 

EXP.  37.  —  To  small  pieces  of  copper  add  dilute  (50  per  cent.)  nitric 
acid,  red  fumes  appear  in  generator  (see  EXP.  38),  but  a  colorless  gas 
collects  over  the  tub. 

Reaction  (irregular,  don't  attempt  to  remember  it)  :  — 

/ 
Cu3  -f-  8  H  X  03  =  3  Cu  2  X  03  +  4  H,0  +2X  0 

nitrugen 
dioxide 

After  the  action  has  ceased,  filter  water  in  flask,  evaporate,  and  obtain 
blue  crystals  of  Cu  2  X  O3. 

EXP.  38.  —  Admit  to  test-tube  containing  X  O  a  bubble  of  O  (or  air). 
Red  fumes  of  Xo04  appear. 


2X0      +     0,     = 


nitrogen 
tetroxide 


These  fumes  are  very  soluble  in  water,  and  the  water  slowly  rises  to 
take  the  place  of  the  dissolved  gas.  If  air  is  admitted,  of  course  the 
water  will  not  entirely  fill  the  test-tube,  as  the  X  will  remain  undis- 
solved  above  the  water. 


EXP.  39. — Into  a  test-tube  put  a  small  quantity  (4  gms.)  of  sodium 
nitrate  (or  K  X03)  and  2  gms.  of  sulphuric  acid.  Carefully  heat.  Col- 
lect nitric  acid  in  a  narrow,  deep  test-tube,  well  cooled  by  sinking  to  its 
mouth  in  cold  water.  [Sink  test-tube  by  tying  stone  to  the  bottom. 
Don't  breathe  the  fumes.  ] 

2XaX03     +     H.,S04     =     Xa,S  O4     +     2  H  X  O3 
- 


60  CHEMICAL   PRIMER. 

Nitric  acid  (old  name  aqua  fortis)  is  prepared  by  heat- 
ing sulphuric  acid  with  sodium  nitrate  (but  see  acid-.ialts). 
It  is  a  colorless  (if  pure),  fuming,  corrosive  liquid. 

EXP.  40. — Place  a  quill  in  H  N  03  and  heat.     The  quill  turns  yellow. 

EXP.  41.— To  dilute  H  NO>.dd  a/rystal  of  Fe  S04;  then  add  a  few 
drops  of  H2  S  04.  A  brown  compound  (Fe  SO^,  N2  02)  slowly  forms 
about  the  crystal.  This  is  a  good' test  for  H  N  03  and  other  nitrates. 

EXP.  42. — Throw  a  small  crystal  of  potassium  nitrate  upon  a  red-hot 
coal.  The  coal  burns  rapidly  (almost  explosively). 

Nitric  acid  stains  organic  matter,  as  the  skin,  nails, 
etc.,  a  dingy  yellow.  It  is  a  powerful  oxidizing  agent, 

as  are  all  the  other  nitrates. 

EXP.  43.—  Spread  upon  a  piece  of  clean  copper  (also  upon  a  piece  of 
iron)  a  thin  layer  of  paraffine.  Write  upon  each,  taking  care  not  to 
scratch  the  metal.  Upon  the  writing  put  nitric  acid  (50  per  cent.).  It 
etches  the  words  by  oxidizing  the  metals,  dissolving  and  uniting  with 
the  metallic  oxides. 

Nitric  acid  is  used  in  etching  upon  copper  and  iron 
(copperplate,  swords,  razors). 

EXP.  44. — Into  a  test-tube  containing  nitric  acid,  drop  a  piece  of  gold- 
leaf  and  heat.  It  does  not  dissolve.  Add  a  few  drops  of  hydrochloric 
acid.  The  gold  rapidly  dissolves,  forming  Au  C13  in  solution. 

Nitric  acid  (about  3  parts)  and  hydrochloric  acid  (5 

parts)  form  aqua  regia,  the  solvent  of  gold  (and  plati- 
num). 


EXP.  45.  —  Place  in  a  flask  a  little  ammonium  chloride  (sal  ammoniac) 
with  an  equal  weight  of  calcium  oxide  (quicklime),  each  finely  pulver- 
ized. Add  a  little  water  and,  quickly  closing  flask,  heat  upon  sand  bath. 
Dry  gas  by  passing  through  bottle  containing  Ca  O.  Collect  by  dis- 
placement of  air  in  receiver.  (See  Fig.  21.)  ["Drying  tube"  may  be 
dispensed  with  and  gas  passed  directly  from  flask  into  receiver.  Don't 
breathe  too  much  of  the  gas.] 

2H4NC1    +     CaO    = 


NITROGEN. 


61 


Fiy.  21. — A — sand  bath;  B— drying  tube;  C— receiver. 

EXP.  46  (45  concluded). — Quickly  close  mouth  of  bottle  of  ammonia 
by  perforated  rubber  cork,  through  which  passes  a  glass  tube  drawn  to 
a  fine  point  and  connected  with  water  colored  red  by  slightly  acidulated 
litmus  solution.  Hasten  the  action  by  forcing  air  into  lower  flask 
(through  tube  A  B,  Fig.  22,  till  a  few  drops  of  water  reach  the  receiver 
(C)  of  ammonia.  The  gas  dissolves  so  rapidly  in  the  water  that  a  par- 
tial vacuum  is  formed,  and  the  outside  atmospheric  pressure  acting 
through  A  B  produces  the  "ammonia  fountain."  The  water  turns  blue 
as  it  enters  the  receiver. 

Ammonia  is  a  colorless 
gas,  with  pungent  odor.  It 
is  much  lighter  than  air.  It 
is  very  soluble  in  water, 
700  gals,  dissolving  in  a 
single  gallon  of  water  at  15° 
(1000  vols.  at  0°,  see  coal 
gas).  It  not  only  dissolves, 
but  unites  with  water 

Reaction : — 

H.N  +  H2O  =  H,N  HO 
forming  ammonium  hydrate 
("ammonia    water,"    hW-s- 

horn,  etc.).  \  Fi.  ^-^oa*  Fount*u,. 

• 

y  ^ 


CHEMICAL   PRIMER. 


The  ammonium  grouping  can  be  passed  from  compound  to  compound 
like  an  element,  and  hence  is  a  compound  radical.  (See  AMMONIUM.  ) 
In  concentrated  "ammonia  water"  there  is  probably  a  large  excess  of 
the  gas  dissolved  (more  than  unites  with  the  water).  Ammonium 
hydrate  (or  ammonia  in  the  presence  of  moisture)  has  a  strong  alkaline 
reaction.  It  has  been  called  the  "volatile  alkali,"  because  its  effect 
upon  vegetable  colors  is  only  temporary.  Prove  this  by  dipping  red 
litmus  paper  into  dilute  ammonia  water  and  noticing  that  the  red  color 
returns  again  after  a  few  hours.  When  the  color  of  cloth ,  stain  ed  by 
an  acid,  has  been  restored  by  "ammonia  water,"  the  ammonium  salt 
should  be  thoroughly  washed  out  with  water,  or  the  red  spot  returns. 
(See  CHEMISTRY  or  CLEANING.) 

"  Evaporation  COOls."  This  means  that  when  a  substance  evapo- 
rates it  absorbs  heat  from  what  is  near  by.  (See  sulphur  dioxide,  AP- 
PENDIX.) Wet  one  hand  and  pass  both  hands  rapidly  through  the  air. 
The  wet  hand  is  sensibly  colder  from  the  evaporation  of  the  water. 
Pour  a  little  ether  upon  the  thermometer  bulb.  The  ether  quickly 
evaporates  and  the  mercury  falls. 

A  pressure  of  about  4J  atmospheres  (at  0°)  converts 
gaseous  into  liquid  ammonia.  The  evaporation  of  liquid 
ammonia  produces  intense  cold  ( — 40°).  Advantage  is 
taken  in  the  arts  of  this  fact  to  produce  ice  artificially. 


In  a  strong  generator,  A,  is  placed 
ice  water  saturated  with  ammonia 
gas  (l,000vols.  in  one).  This  is  con- 
nected with  an  equally  strong  receiver 
D,  by  the  tube  B.  Receiver  D  is 
placed  in  cold  water.  Heat  is  applied 
to  A  and  the  great  pressure  of 
escaping  gas  converts  the  gas  into  a 
liquid  in  D.  \Vater  is  now  placed  in 
vessel  C.  Generator  A  is  cooled  and 
the  liquid  ammonia  in  D  evaporates 
and  is  reabsorbed  by  water  in  A. 
The  evaporation  produces  sufficient 
cold  (takes  away  or  absorbs  sufficient 
heat)  to  freeze  water  in  C.  Other  sub- 
stances th.Mi  ammonia  irr  lie  used 


Fijr.  23.— Ire  Machine. 
for  this  purpose,  all,  however,  involving  the  principle  of  evaporation 


CARBON.  63 


Nitrogen  and  hydrogen  do  not  unite  directly  to  form  ammonia.,  but 
when  decomposition  is  taking  place  in  organic  substances,  and  these  two 
elements  are  leaving  their  old  compounds,  they  unite.  Elements  just 
leaving  their  old  compounds  are  said  to  be  in  the  nascent  state,  and 
they  have  a  much  greater  tendency  to  form  new  compounds. 


CHAPTER    XXI, 


CARBON. 

• 

Carbon  is  a  very  abundant  element.  It  forms  a  large 
proportion  of  vegetable  and  animal  tissues,  and  is  a  prom- 
inent constituent  of  limestone,  marble,  etc.  (carbonates). 
We  know  it  in  three  allotropic  states:  — 

1.  Diamond. 

'2.  Graphite  (plumbago,  black  lead). 

3    Amorphous  Carbon  (uncrystallized). 

Graphite,  mixed  with  a  little  Sb  and  S,  is  used  to  make 
common  "lead  pencils."  Mixed  with  clay,  it  makes  cru- 
cibles, the  most  refractory  (difficult  to  melt,  or  of  ores, 
difficult  to  reduce)  known. 

Amorphous  Carbon  (more  or  less  impure)  includes 
charcoal,  mineral  coal  (the  remains  of  vegetation  of  the 
carboniferous  age),  coke,  peat,  animal  charcoal  (bone 
black),  soot,  lamp-black,  and  gas-carbon. 

XOTE.  —  For  fuller  description  of  the  above  and  of  all  such  substances 
briefly  mentioned  in  this  primary  work,  see  the  dictionary  and  cyclopae- 
dia. Every  Hkrh  School  should  have  an  unabridged  dictionary  and  a 
cyclopa-dia  pii<~>d  //•//».-.-'  .«7<n/  (/•-  /••*/»  readiiy  r>J\'r  to  thet/i. 


64  CHEMICAL  PRIMER. 

Carbon  for  a  long  time  resists  decay.  Fence  posts  are 
charred  to  preserve  them.  Neither  acids  (except  nitric) 
nor  alkalies  affect  it. 

EXP.  47.— Collect  in 
test-tube  over  mercury 
(or  by  displacement  of 
air)  H3  N.  Introduce 
into  the  gas  a  piece  of 
fresh  burned,  dry  char- 
coal, mounted  on  wire 
attached  to  perforated 
cork,  and  quickly  dip 
the  mouth  of  test-tube 
beneath  mercury.  The 
Hg  rises  in  test-tube,  be- 
cause C  absorbs  the 
Fig.  24. -Mercuric  Tub.  H3N  in  its  pores. 

NOTE. — Chisel  out  of  hard  wood  a  trough  5  inches  long,  1  inch  wide, 
and  1  inch  deep.  Nail  a  lead  post  to  one  or  both  ends  to  support  small 
test-tube.  This  makes  a  very  good  mercuric  pneumatic  tub,  but  the 
mercury  must  not  come  in  contact  with  the  lead.  To  avoid  this  the 
supports  may  be  made  of  wood.  Use  narrow  test-tubes  and  keep  them 
from  the  side  of  the  tub,  else  the  air  creeps  in. 

Carbon  absorbs  many  times  its  bulk  of  gases,  condens- 
ing them  in  its  pores.  Fresh  burned  charcoal  is  a  good 
"disinfectant"  for  foul  gases.  They  are  destroyed 
within  its  pores  by  the  absorbed  O ;  i.  e.,  by  oxidation  (so 
that  C  is  not  a  disinfectant  in  a  strict  chemical  sense,  but 
its  action  is  mechanical).  O  is  the  real  disinfectant. 

EXP.  48.— Finely  pulverize  charcoal  by  rubbing  two  sticks  together, 
or,  if  animal  charcoal  is  used,  by  grinding  in  mortar,  and  place  upon 
filter.  Slowly  moisten  with  distilled  water.  Let  diluted  ink  (or  indigo 
solution,  vinegar,  etc.)  fall  drop  by  drop  upon  the  charcoal  from  an 
ordinary  paper  filter  above  it.  The  filtrate  from  charcoal  is  colorless. 

Charcoal  is  a  good  decolorizing  agent.  Animal  char- 
coal is  largely  used  in  sugar  refineries  to  remove  soluble 
impurities  and  color. 

\? 


CARBON. 


66 


EXP.  49. — Heat  upon  platinum  foil  a  piece  of  sugar  (or  other  organic 
matter,  as  tartaric  acid,  flesh  or  vegetable).  It  chars  (turns  black,  as  the 
more  volatile  constituents  are  driven  off,  leaving  the  carbon  free). 

Charring  is  a  good  test  for  carbon  (or  for  organic  mat- 
ter) 

EXP.  50. — Upon  charcoal  put  a  little  litharge  (Pb  0).  Heat  in  the 
blow-pipe  flame.  The  0  is  taken  by  the  C  leaving  the  Pb  fret  (uncom- 

bined).  / 

2PbO     +     C     =    Pb,    -f-     C02 

metallic 
lead 

Carbon  is  a  good    deoxidizing  or   reducing  agent. 

Heated  with  the  oxides  of  most  metals  it  deoxidizes  them, 
and  is  thus  of  special  use  in  reducing  ores  that  are  oxides 
''or  carbonates,  since  great  heat  breaks  up  the  carbonate 
grouping,  setting  C  O2  free,  and  leaving  an  oxide  behind). 


EXP.  51. — Upon  pieces  of  marble  (Ca  C03)  in  a  flask,  pour  dilute  (2C 
per  cent. )  H  Cl.     Collect  gas  by  displacement  of  air. 

Reaction  (class  4):    Ca  C03  +  2  H  Cl  —  Ca  C12  +  H20  +  C  02 

carbonate  acid  salt  water          carbonic 


oxide 


Fig.  25. 

•-v-vi 


4JL+ 


66  CHEMICAL   PRIMER. 


Carbon  dioxide  (carbonic  oxide,  carbonic  anhydride, 
old  name  carbonic  acid)  is  a  colorless  gas,  with  slightly 
acid  taste.  It  is  much  heavier  than  the  air  (sp.  gr.  1.5, 
with  H  as  standard  22)  in  which  it  exists  free,  forming 
about  ^TOCTT  by  volume. 


EXP.  52.  —  Into  a  jar  of  C  02  introduce  a  lighted  taper.      It  is  extin- 
guished. 


.  53.  —  Arrange  short  lighted  candles  along  an  inclined  (not  too 
steep,  else  draft  is  produced)  trough  (piece  of  gutter).  Pour  a  large 
receiver  of  C  02  into  the  top  of  the  trough.  The  candles  go  out  in  order 
as  C  02  reaches  them. 

EXP.  54.  —  Put  a  mouse  into  a  receiver  of  C  02.     The  animal  dies. 

Carbon  dioxide  does  not  support  combustion  and  is 

not  inflammable.  Though  not  poisonous  in  a  strict 
sense  of  the  word,  yet  animals  die  from  suffocation  in  air 
containing  about  five  per  cent,  of  the  gas.  It  hinders 
the  elimination  of  the  same  gas,  C  O2  from  the  lungs  (but 
see  C  O2  in  APPENDIX). 

EXP.  55.  —  Burn  Mg  ribbon  in  a  jar  of  C  02.  Black  particles  of  carbon 
appear  mixed  with  the  white  oxide. 

C02     +     Mg2     =    2MgO     +     C 

white  black 

Dissolve  oxide  in  dilute  H  N  03  and  C  is  made  more  distinct.  C  02 
supports  the  combustion  of  magnesium,  but  by  a  supporter  of  combus- 
tion in  general  we  mean  a  substance  that  supports  the  combustion  of 
hydrocarbons. 

Exp.  56.  —  Repeat  EXP.  33. 

Lime-water  is  the  test  for  C  02.  No  other  gas  will  (1) 
extinguish  flame  and  (2)  render  lime-water  milky. 

EXP.  57.  —  Hold  the  breath  a  short  time  and  then  expel  the  air  into  a 
receiver.  Test.  It  extinguishes  the  flame  of  taper  and  turns  lime-water, 
shaken  up  in  the  receiver,  milky. 


CARBON. 


67 


Fig.  26. 


Animals  exhale  0  O.,  from  the 
lungs  as  a  waste  product.  They 
use  up  O  from  the  air  and  replace 
it  by  C  O2. 

EXP.  58. — Place  a  small  branch  having 
numerous  and  fresh  leaves  in  a  tall  receiver 
(prepared  as  in  Fig.  26)  of  spring  or  brook 
water  (?'.  e. ,  water  that  has  been  sufficiently 
exposed  to  carry  much  air  dissolved)  and 
place  apparatus  a  few  hours  in  direct  sun- 
shine. O  is  evolved  and,  together  with  a 
little  X  and  traces  of  C  02  driven  off  by  the  sun's  heat  (of  course  a 
little  O  is  also  driven  off  by  sun's  heat),  collects  in  top  of  receiver.  Test 
by  very  slender  and  glowing  taper.  The  gas  is  found  to  be  principally 
oxygen. 

Plants  in  sunshine  exhale  through  their  leaves  O  (except 
certain  low  orders),  using  up  C  O^  of  the  air  and  building 
the  C  into  their  tissues.  The  leaves  of  plants  are  often 
compared  to  the  lungs  of  animals,  except  we  must 
remember  that  the  process  is  reverse.  They  receive  the 
air  through  little  stomata  (mouths)  on  the  under  side  (prin- 
cipally). But  in  some  important  respects  the  leaves  cor- 
respond to  the  digestive  organs  of  animals  (including 
glands  preparing  chyle  for  the  general  circulation,  viz., 
"  mesenteric  glands"  and  the  liver).  The  plant  gets  vastly 
more  food  (by  weight)  from  the  air  than  from  the  richest 
soil.  The  smaller  portion  which  it  gets  from  the  soil  is, 
however,  an  essential  portion,  and  it  will  not  flourish  in 
poor  soil. 

Plants  purify  the  air  for  animals,  and  animals  by  a 
reverse  process  supply  from  their  own  waste  the  needed 
elements  of  plant  food.  Carbon  dioxide  is  also  formed  in 
large  quantities  by  the  decay  of  organic  matter.  The 
proportion,  however,  of  C  O2  in  the  air  remains  practi- 
cally the  same  from  year  to  year. 


68  CHEMICAL  PRIMER. 


C  02  tends  to  collect  in  old  wells  and  in  unventilated  portions  of 
mines.  It  is  called  by  miners  choke-damp.  Wherever  a  light  is  ex- 
tinguished by  C  0.2,  it  is  unsafe  to  go. 

EXP.  59. — Place  a  short  lighted  candle  on  a  rubber  cork  and  intro- 
duce it  into  the  bottom  of  a  vertical  glass  tube,  which  the  cork  tits. 
The  candle  goes  out.  In  the  tube  suspend  a  smaller  tube  and  introduce 
the  lighted  candle  as  before.  It  burns  steadily.  The  heated  air  (and 
C  O2)  rises  in  the  small  tube  (upward  draft)  and  the  fresh  air  containing 
0  falls  between  it  and  the  larger  tube. 

Two  openings,  at  least,  are  necessary  for  proper  ventilation.  In 
mines  where  it  is  possible,  two  shafts,  one  at  each  end,  with  a  fire  at 
the  base  of  either,  answers  the  purpose.  Very  complex  arrangements, 
however,  have  to  be  made  in  many  cases  to  force  air  into  the  various 
parts  of  large  mines.  Plenty  of  fresh  air  is  the  only  preventive  to  keep 
fire-damp  (marsh  gas  C  H4)  and  C  02  from  accumulating  in  dangerous 
quantities. 

EXP.  60. — Hold  the  breath  a  short  time  and  then  expel  it  into  a  jar 
and  close  by  rubber  cork.  Set  aside  in  a  warm  place  for  a  day  or  two 
and  then  open.  A  very  offensive,  putrescent  odor  greets  the  sweetest- 
breathed  experimenter.  (C  0^  has  no  odor. )  [This  experiment  may, 
perhaps,  best  be  performed  at  home.] 

Churches,  school-rooms,  bedrooms,  etc.,  should  be  very 
thoroughly  ventilated,  not  so  much  to  free  them  from  the 
injurious  C  O,  as  to  remove  the  poisonous  "animal 
vapor1'  (moisture  in  suspension)  thrown  off  from  the  lungs. 
This  "  vapor  "  holds  all  manner  of  organic  impurities  in 
solution. 

EXP.  61. — Fill  a  narrow,  deep  test-tube  with  C  02.  Close  with  the 
thumb  and  open  under  cold  water  (but  previously  boiled),  pressing  the 
mouth  a  few  inches  below  the  surface.  Close  the  test-tube,  remove  and 
shake.  Part  of  the  C  02  dissolves.  Open  under  water  and  repeat  shak- 
ing. In  this  way  the  test-tube  of  C  02  may  be  dissolved  in  a  test-tube 
of  water. 

Water  at  15°  dissolves  one  vol.  of  C  02,  but  if  the  gas  is  under  press- 
ure, it  dissolves  much  more  (by  weight). 


CARBON. 


69 


"Soda  Water"  is  nothing  but  a  solution  of  C  O,  under 
pressure  in  water.  It  probably  receives  ics  inappropriate 
name  because  of  its  effervescence  when  relieved  of  pressure 
(like sodium  carbonate,  "soda,"  when  mixed  with  a^i  acid). 

C  02  has  b  ieii  condensed  to  a  liquid,  and  by  rapid  evaporation  of  a 
part,  the  rest  is  solidified  (frozen),  forming  a  snow-white  solid.  This 
solid  is  so  coid  that  whca  touched  it  produces  the  same  effect  as  red- 
hot  iron  (see  similar  condensation  of  S  02,  APPENDIX). 

As  we  have  seen,  C  O2  and  H^O 
are  the  two  great  products  of  ordi- 
nary combustion.  The  chemistry 
of  a  burning  candle  is  in  a  general 
sense  very  simple.  The  wick  is  first 
raised  to  the  igniting  point,  the 
heat  melts  the  tallow  (composed 
chiefly  of  H  and  C  combined),  and 
the  liquid  is  then  drawn  up  by  cap- 
i  1  lary  attraction  into  the  wick.  Here 
the  great  heat  changes  the  liquid 
tallow  into  the  gaseous  state  (with 
decomposition  into  various  hydro- 
carbons). Flame,  is  burning  gas. 
The  flame  is  hollow,  as  no  O  can 
penetrate  to  its  center,  and  the  hol- 
low is  filled  with  the  unburnt  gases. 
'These  may  be  drawn  away  by  a 
fine  glass  tube  and  burned  at  its  end,  if  the  candle  is  a 
large  ont.)  In  floating  outward,  the  C  from  the  decom- 
posed hydrocarbons  becomes  white  hot  and  gives  out  light, 
but  soon  meets  the  O  of  the  air  and  becomes  C  O2  at  the 
instant  it  ceases  to  give  light.  Outside  is  a  faintly  blue 
cone,  cup-shaped  at  the  bottom  and  composed  of  burning 
H  (and  C  O).  If  a  cold  piece  of  glass  or  porcelain  is  in- 


Fig.  27. 


/ 


70 


CHEMICAL   PRIMER. 


troduced  into  the  flame,  the  C  is  lowered  below  the  ignit- 
ing point  and  is  deposited  as  smut.  The  H2O  (steam)  is 
condensed  and  deposited  also.  We  notice  this  condensed 
steam  upon  the  cold  chimney  when  the  lamp  is  first 
lighted,  but  it  evaporates  as  the  chimney  becomes  hot. 

x 

Illuminating'  gas  is  made  from  bituminous  coal  by  heating  in  retorts 
and  collecting  volatile  hydrocarbons  in  a  holder.  It  contains  various 
gases,  H,  C  0,  C  H4  (marsh  gas,  "fire  damp"  of  miners),  C2H4  (olefi- 
ant  gas,  ethylene),  C6H6  (vapor  of  benzol),  etc.,  and  (before  purifica- 
tion) others  that  must  be  removed,  as  H3N,  C  02,  H2S  (and  other  sul- 
phur compounds),  besides  vapor  of  "tar."  Tar  is  a  very  complex  sub- 
stance, from  which  the  aniline  dyes,  carbolic  acid,  etc.,  are  obtained. 
H3N  may  be  removed  by  passing  through  water  (or  H  Cl,  old  method), 
C  O2  by  passing  through'  "pans"  of  lime  (Ca  0),  and  the  sulphur  com- 
pounds by  passing  over  ferric  hydrate.  The  last  reaction  may  be  rep- 
resented thus: — 


Fe,6HO 

ferric 
hydrate 


H2S 

hydrogen 
sulphide 


Fig.  23.— Section  of  Gas  Meter. 


2Fe2HO     +     2  H20     +     S 

ferrous  water  free 

hydrate  sulphur 


On  exposure  to  the  air,  ferrous 
hydrate  becomes  ferric  hydrate,  and 
the  material  may  be  repeatedly  used 
till  the  free  sulphur  forms  from  40  to 
50  per  cent.  The  tar  vapor  condenses 
and  runs  into  the  "tar  well."  The 
refuse  (coke)  is  left  behind  in  the 
retorts. 

The  purified  gas  is  measured  by 
the  meter  and  passes  into  the  holder, 
from  which  it  is  distributed  to  con- 
Illuminating gas  is  also 


The  three  arrows  represent  the  rota-  made  from  crude  petroleum,  more 
tion  or  the  chambers;  the  solitary  arrow 

the  escape  of  the  gas  from  chamber,    complex  machinery  being  used. 
Gas  enters  through  the  U-shaped  center. 

Bunsen's  Burner  is  represented  in  Fig.  21  and  is  used  when  heat, 
not  light,  is  wanted.  The  gas  is  mixed  with  the  air,  drawn  in  through 
openings  at  the  side.  The  flame  is  condensed,  is  much  hotter,  and  does 
not  smut  cold  glass.  y^~  K^  ^  ^ 

.  ^-^4^4      '  JJL 


CARBON, 


71 


.  29. 


EXP.  62.— Heat  in  ex- 
treme tip  of  blowpipe  flame 
the  end  of  a  clean  copper 
wire.  It  turns  black,  i.  €., 
is  oxidized,  forming  Cu  O. 
Heat  in  the  midst  of  flame 
nearer*the  blowpipe.  The 
Cu  O  is  reduced  (deoxi- 
dized) and  the  bright  me- 
tallic copper  appears. 

By  means  of  the  blowpipe^we^may  do  two  things, 
oxidize  most  metals  (a  very  small  portion  is  sufficient  for 
tests)  and  reduce  their  oxides. 

At  A  (Fig.  29)  a  substance  may  be  oxidized,  because  here  we  have  an 
excess  of  0  thrown  forward  from  the  blowpipe  and  highly  heated,  The 
flame  in  the  center  at  B  is  reducing,  for  here  there  is  an  excess  of  highly 
heated  carbon.  The  reducing  flame  is  best  produced  by  holding  the  noz- 
zle of  blowpipe  a  very  short  distance  from  the  flame  instead  of  in  it- 
The  blowpipe  is  a  very  valuable  instrument  in  the  analysis  of  ores, 

EXP.  63. — Two  inches  above  a  gas  burner  hold  a  fine  wire  gauze  and 
ignite  jet  of  gas  above  the  gauze.  It  burns  above,  but  not  below.  The 
wire  being  a  good  conductor  of  heat  reduces  the  gas  below  the  igniting 
point,  and  the  flame  cannot  pass  through  the  gauze. 

Davy's  Safety  Lamp  used  by  miners  is 
essentially  a  lamp  surrounded  by  a  wire 
gauze.  The  flame  cannot  pass  through 
this  to  ignite  the  "fire-damp"  (C  H4  marsh 
gas).  This  dangerous  gas  explodes  vio- 
lently when  mixed  with  air  and  ignited 


EXP.  64 — Into  a  flask  put  a  small  quan 
tity  of  oxalic  acid  crystals  and  cover  with 
strong  sulphuric  acid.  Heat  gently  and 
pass  gases  through  wash  bottle  containing 
strong  solution  of  K  H  0.  Collect  over 
water. 


H2CA  =  H20  +  C  O2  +  C  O  Ffc.  30.-Wash  B. 


72  CHEMICAL    PRIMER 


The  sulphuric  acid  absorbs  H20  from  the  oxalic  acid,  breaking  up  the 
molecule.  The  K  H  0  solution  absorbs  the  C  02, becoming  K2C  03  (and 
H20),  and  the  C  O  is  collected  in  receiver.  Test  by  lighted  taper.  It 
bupis  with  bluish  flame, 

Carbon  monoxide  C  O  (carbonous  oxide,  old  name  car- 
bonic oxide)  is  a  colorless  poisonous  gas  formed  by  burn- 
ing C  in  a  close  atmosphere.  Escaping  from  hot  stoves 
through  the  pores  of  the  iron  into  ill-ventilated  rooms,  it 
causes  headache.  In  large  quantities  it  speedily  produces 
coma  and  death.  Its  pale,  lambent  flame  is  frequently 
seen  when  fresh  hard  coal  is  placed  upon  the  grate, 

NOTE.— Organic  chemistry  may  be  considered  as  carbon  continued 
The  previous  rules  for  writing  formulas  and  names,  which  hold  so  gen- 
erally in  inorganic  chemistry,  fail  in  numberless  instances  to  meet  the 
requirements  of  organic  chemistry,  as  we  shall  see.  Notice  that  the 
order  of  C  H  and  0  is  usually  used  in  organic  chemistry  instead  of  H  C 
and  0.  (See  marsh  gas,  vapor  of  benzol,  etc.,  above,  and  also  OKGANIC 
CHEMISTRY.  ) 


CHAPTER    XXII. 


BINARY    ACID-    AND    SALT-FORMERS, 

FLUORINE,    CHLORINE,   BROMINE,    IODINE,   AND  CYANOGEN. 

EXP.  65. — Into  a  small  flask  on  a  sand-bath,  put  equal  weights  of 
common  salt  and  manganese  dioxide,  well  mixed.  Add  sufficient  water 
t.o  make  thin  paste.  Pour  in  through  funnel  a  small  quantity  of  sul 
Dhuric  acid  (commercial)  and  collect  gas  in  large  test-tube  over  hot 
water,  or  by  displacement  of  air  in  deep  receivers.  Heat  should  be 
ipplied  to  flask  to  drive  off  the  last  (and  greater  portion)  of  the  gas.  A 
ouble  reaction  takes  place: — 

(1)— H2S  04    +    2  Na  Cl    =    Na,S  04    +    2  H  Cl 

/ 
(2)— Mn  0 .,    +    4  H  Cl    =    Mn  Cl,    +    2  H.,0    4-    Cla 


BINARY  ACID-  AND  SALT- FORMERS.        73 


The  gas  may  be  freed  from  H  Cl  by  passing  through  wash  bottle  (see 
Fig.  30)  of  cold  water.  It  may  be  dried,  if  desired,  by  passing  through 
strong  H.2S  04  in  the  same  manner,  and  then  collected  by  displacement 
of  air 

Caution. — Care  should  be  taken  not  to  breathe  (except  in  minute 
quantities)  chlorine,  cyanogen,  or,  in  short,  any  gases  or  products  that 
are  poisonous.  Small  quantities  of  such  gases  should  be  used  in  experi- 
ments. If  larger  quantities  are  desired,  they  should  be  made  under  a 
"gas  chimney,"  or  near  a  window  with  outward  draft. 

Chlorine  is  a  greenish- yellow, poisonous  gas  of  a  suffo- 
cating odor.  When  very  dilute  it  produces  coughing 
(relieved  by  inhaling  dilute  ammonia),  and  breathed  in 
larger  quantities,  inflammation  of  the  trachea  and  bron- 
chial tubes.  It  is  2.5  times  heavier  than  air.  It  is  an 
abundant  element,  but  is  not  found  free  in  nature. 


EXP.  66. — Burn  a  jet  of  H 
in  Gl  and  test  product  by  blue 
litmus,  (Fig.  31.) 


H 


HC1 


EXP,  67.—  Into  a  jar  of  Cl 
plunge  a  small  lighted  pitch, 
wood  taper.  It  burns  awhile 
with  red,  smoky  flame,  but 
soon  goes  out.  The  Cl  unites 
with  H  of  the  taper,  setting  the 
C  free  as  smoke.  Test  by  blue 
Fig.  31.  litmus. 

Cl  has  a  great  affinity  for  H.  Upon  this  affinity  de- 
pends its  value-  as  a  disinfectant.  H  is  an  essential  con- 
stituent of  many  foul  gases  Cl  destroys  them  as  it 
destroys  coloring  matters.  (See  EXP.  72.) 

EXP.  68.  —  Upon  paper  containing  printer's  ink  write  with  common 
ink  i  is  i  in  tannate  Fe3  2  C.27H19017)  and  lower  into  a  jar  of  CL  The  com- 
mon ink  is  bleached,  but  the  printer's  ink  (linseed  oil  and  lamp-black  , 
C)  is  unaffected 


<£-•• 


74  CHEMICAL   PRIMER. 

EXP.  69- — Into  a  black  bottle  containing  cold  water  pass  Cl  gas  (puri 
fied  of  H  Cl).  The  Cl  dissolves  (3  vols.)  and  forms  "chlorine  water." 
Set  aside  as  a  reagent. 

EXP.  70. — Expose  a  little  chlorine  water  in  a  beaker  to  the  sunlight 
for  a  few  hours.  Place  it  beside  a  beaker  of  fresh  chlorine  water  from 
dark  bottle,  and  to  each  add  a  piece  of  blue  litmus  paper.  The  fresh 
chlorine  water  bleaches,  the  other  turns  the  litmus  red.  The  light  en- 
abled the  Cl  to  decompose  the  water  thus:— 

C12     +     H20     =    2HC1    +     0 

("Light  farors  chemical  change.") 

EXP.  71. — Into  a  beaker  containing  Cl  water  let  fall  a  few  drops  of 
red  ink  (cochineal),  or  indigo  solution,  aniline  purple,  etc.  The  color  is 
discharged. 

EXP.  72. — Into  a  beaker  of  chlorine  water  introduce  a  piece  of  calico. 
The  color  is  discharged,  except  from  those  portions  colored  by  mineral 
substances, 

Chlorine  is  a  powerful  bleaching  agent,  and  for  this 
purpose  is  largely  used  in  the  arts.  It  bleaches  (and  dis- 
infects) in  two  ways : — • 

1.  By  removing  H  from  the  substance 

2.  By  removing  H   from   water,  setting  free    "nascent"   O,  which 
bleaches.     (Thus  Cl  bleaches  by  proxy. }     Dry  Cl  does  not  bleach. 

Bleaching  powder,  "chloride  of  lime,"  is  mixture  of  calcium  hypo- 
chlorite  (Ca  2  Cl  0)  and  calcium  chloride  (Ca  C12).  A  dilute  acid  sets 
chlorine  free  with  promptness.  Moisture  and  exposure  sets  chlorine 
free  slowly,  therefore  bleaching  powder  is  used  as  a  disinfectant.  Acids 
set  the  chlorine  free  rapidly.  Cl  may  be  conveniently  prepared  from 
bleaching  powder. 

EXP.  73. — Into  a  jar  of  Cl  sprinkle  antimony  (powdered  with  a  file). 
It  takes  fire  and  fills  the  jar  with  white  fumes.  (Sb  C15,  poisonous.) 

EXP.  74.— Bum  Mg  ribbon  in  jar  of  Cl,  igniting  it  first  in  alcohol 
or  Bunsen's  flame 

Cl  has  a  great  affinity  for  the  metals,  (Sb  is  semi-metal. ) 
Most  of  them  burn  in  chlorine,  forming  ch]orides.  Chlo- 
rine, as  we  have  seen,  does  not  unity  with  carbon  and 


>  I 


BINARY  ACID-  AND  SALT-FORMERS.        75 

therefore  does  not  support  the  combustion  of  hydrocar- 
bons. 

EXP.  75. — Into  a  test-tube  containing  a  little  common  salt,  pour  strong 
sulphuric  acid,  and  gently  heat.  Collect  gas  in  narrow,  deep  test-tube 
by  displacement  of  air  (holding  mouth  upward). 

2  Na  Cl  +  H2  S  0,  =  Na2S  O4  +  2  H  Cl 

Cover  test-tube  with  thumb  and  open  under  water;  the  water  rushes 
in  violently  and  fills  the  tube. 

Hydrochloric  acid  (hydrogen  chloride,  chlorohydric 
acid,  muriatic  acid)  is  a  colorless,  irrespirable,  acid  gas, 
very  soluble  in  luater  (450  vols.  in  one  at  15°).  The 
liquid  called  hydrochloric  acid  is  really  a  solution  of  the 
gas  in  water  (a  mere  solution). 

EXP.  76. — Dip  a  glass  rod  into  strong  ammonia  water,  and  another 
into  strong  H  Cl  and  bring  the  rods  together.  Dense  white  fumes  of 
ammonium  chloride  appear.  The  reaction  is: — 

H4X  H  O  -f-  H  Cl  =  H4X  Cl  -f  H20 
or  omitting  the  water 

H3  N  +    H  Cl    -    H,X  Cl 

This  is  a  rough  test  for  H  Cl  or  for  free  ammonia. 

EXP.  77. — Boil  in  H  Cl  a  small  piece  of  gold-leaf.  It  does  not  dis- 
solve. Add  a  drop  of  H  X  03,  a  yellow  solution  of  gold  chloride  (AuCl3) 
appears. 

Hydrochloric  acid  and  nitric  acid  form  aqua  regia,  the 
solvent  of  gold. 

EXP.  78. — Repeat  EXP.  6  and  7,  and  also  use  other  soluble  chlorides. 
Soluble  chlorides  precipitate  silver  as  silver  chloride. 

EXP.  79. — Heat  a  little  pulverized  K  Cl  03upon  charcoal  in  the  blow- 
pipe flame.  The  coal  burns  explosively. 

2  K  Cl  03  -f  C3  =  2  K  Cl  +  3  C  02 

The  chlorates,  as  well  as  the  nitrates,  are  good  oxidiz- 
ing agents.  Potassium  chlorate  is  one  of  the  most  impor- 
tant of  the  chlorates. 

'•     . 

yr 


1 


76  CHEMICAL  PRIMER. 

EXP.  80. — In  a  test-tube  thoroughly  mix  a  little  pulverized  K  Br  and 
Mn  02,  moisten  with  water,  add  strong  H2S  04,  quickly  close  by  perfo- 
rated rubber  cork  and  collect  liquid  in  deep  test-tube  coaled  in  water. 
(Exp.  39.)  Heat  to  drive  off  the  larger  portion  of  the  bromine.  Pour 
into  glass -stoppered  bottle  and  preserve. 

(1)--H2S04     +     2KBr     -     K2S  04     +     2  H  Br 
"  (2)— Mn  02     +     4  H  Br  Mn  Br2     +     2  H20  +     Br, 

Bromine  is  a  volatile,  poisonous,  dark  red  liquid,  very 
similar  in  its  properties  to  chlorine,  but  less  active. 

Many  experiments  analogous  to  those  under  Cl  may  be  performed 
with  bromine  vapor.  Thus,  Br  bleaches  and  unites  with  H  to  form 
hydrobromic  acid.  H  Br  and  other  soluble  bromides  precipitate  silver 
as  yellow  silver  bromide,  which  blackens  in  sunlight  like  silver  chloride. 
(Perform  experiments  and  write  reactions.)  Br  is  not  a  very  abundant 
element.  Potassium  bromide  is  used  in  medicine  to  repress  excessive 
reflex  action  (nervousness,  hysterics,  etc.). 

EXP.  81. — Into  a  test-tube  put  solution  of  K  Br  and  add  a  drop  or 
two  of  chlorine  water. 

Reaction:    K  Br     -f-     Cl     =     K  Cl     +     Br  (free) 
The  solution  becomes  yellow.     Bromine  water  is  yellow. 

This  experiment  shows  the    superior  chemism   (chemical  affinity) 

or  activity  of  chlorine  and  a  method  of  testing  for  bromides. 


EXP.  82.  —  In  a  deep  test-tube  place  pulverized  K  I  and  Mn  02  well 
mixed.  Moisten,  and  adding  strong  H.,8  04,  gently  heat.  Violet  colored 
vapor  of  iodine  appears.  Set  aside  for  a  few  moments.  Iodine  con- 
denses on  the  sides  of  the  test-tube. 

Iodine  is  a  grayish-black  solid  with  metallic  luster. 
It  is  a  comparatively  rare  element. 

EXP.  83.  —  To  tincture  (solution  in  alcohol)  of  iodine  very  dilute  (with 
water),  add  dilute  solution  of  starch  paste.  Blue  iodide  of  starch 
appears.  [That  the  compound  is  not  a  very  stable  one  may  be  shown 
by  gently  heating.  The  blue  color  disappears,  but  reappears  as  the 
solution  cools.] 


^^>  '»  ^C 

>    :f 


BINARY  ACID-  AND  SALT-FORMERS.        77 

Ex  P.  84. — Boil  a  small  piece  of  potato  in  beaker  of  water.  Filter, 
and,  after  filtrate  is  cold,  add  a  few  drops  of  very  dilute  iodine  tincture. 
Blue  iodide  of  starch  appears. 

Starch  is  a  very  delicate  test  for  free  iodine,  and,  vice 
versa,  iodine  for  starch.  (See  EXP.  85.) 

Soluble  iodides  precipitate  silver  as  silver  iodide,  which  blackens  in 
sunlight.  Iodine  was  formerly  much  used  in  medicine  to  "scatter" 
glandular  swellings,  etc.  It  is  now  less  often  used. 

EXP.  85.  — Into  a  test-tube  put  solution  of  K  I.      Add  two  or  three 
drops  of  starch  solution.      No  blue  color  appears,  because  the  I  is  com- 
bined with  K.      Add  a  few  drops  of  chlorine  water.       The  blue  color 
appears  because  the  Cl  unites  with  the  K  setting  the  I  free. 
KI     +     C1     =     KC1     +     I  (free) 

The  free  I  then  unites  with  the  starch,  forming  the  blue  color. 

This  experiment  shows  the  superior  chemical  affinity  of  chlorine  and 
a  method  of  testing  for  iodides. 


Fluorine  is  the  only  element  which  does  not  unite 
chemically  with  oxygen.  It  is  supposed  to  be  a  colorless 
gas,  but  so  great  is  its  chemical  affinity  that  it  has  not 
been  satisfactorily  isolated  (set  free). 

EXP.  86. — In  a  platinum  or  lead  crucible  place  two  grams  of  pulver- 
ized Fluor  Spar  (Ca  F2)  and  cover  with  strong  H2S  O4.  Goat  a  piece  of 
glass  at  a  gentle  heat  with  paraffine  (or  wax)  and  having  written  a  word 
upon  the  paraffine,  gently  heat  crucible,  and  removing  lamp,  cover  with 
glass.  The  word  is  etched  upon  the  glass.  (Caution,  EXP.  65.) 

(1)— CaF.,     +     H2S04     -     CaS04     +     2HF 
(2)— 4  H  F     +     Si  O2     =     2  H2O    +     Si  F4 

of  the 
glass  (which  see) 

Hydrofluoric  acid  (H  F)  is  used  for  etching  letters  or 
designs  upon  glass.  If  the  gas  is  used,  the  letters  or  de- 
signs are  left  rough  •  but  if  a  solution  of  the  gas  in  water 
'kept  in  gutta  percha  bottles)  is  ^ised,  the  ^tjched  portion 
is  smooth,  /3jC/-\r  t|w^  &&lrY*/  '•  s 

-*l  *»  f~~T~     i[g~+~*A~J  \ 

^">U    >U 

^  ^^^     f 


78  CHEMICAL   PRIMER. 


EXP.  87. — In  a  tube  of  hard  glass  place  a  small  quantity  of  mercuric 
cyanide  (Hg  2  C  N).  Heat  carefully  to  dull  redness  and  collect  gas  in 
test-tube  over  mercury.  Test  by  lighted  taper.  The  gas  burns  with 
beautiful  reddish-purple  flame.  (Caution,  EXP.  65.) 

/ 
(l)-Hg2CN  Hg    +     (ON), 

/  / 

(2)— CN    +    02     =     C02    -f    N 

Cyanogen  (C  N  or  Cy)  is  a  colorless,  pungent,  inflam- 
mable gas  with  strong  peach-blossom  odor.  As  the  mol- 
ecule of  hydrogen  has  been  represented  thus  |  H  H  |  ,  so 
the  molecule  of  free  cyanogen  may  be  represented  thus 

|  C  N  C  N  |  or  C2N2. 

It  is  interesting  as  being  the  first  "compound  radical"  isolated. 
It  forms  binary  salts,  several  of  which  are  very  important.  The 
intensely  poisonous  "prussic"  acid  (hydro-cyanic  acid,  H  C  N)  may  be 
formed  by  the  action  of  sulphuric  acid  on  potassium  cyanide.  (Do  not 
perform  the  experiment.) 

2KCN     +     H2S04  K,S04    +     2HCN 

Prussic  acid  is  used  in  medicine.  Many  patent  medicines  claiming  to 
be  preparations  from  cherry  bark  are  essentially  nothing  but  very  dilute 
solutions  of  hydro-cyanic  acid.  Potassium  cyanide  is  one  of  the  most 
important  of  the  cyanides.  It  is  very  poisonous. 

MISCELLANEOUS  QUESTIONS. 

1 .  Reactions  in  making  0  ? 

2.  How  many  litres  of  0  can  be  made  from  150  grams  of  K  Cl  03? 
[NOTE.— A  litre  of  H  weighs  .0896  grams  (at  0°  and  barometer  760 
mm),  and  a  litre  of  0  weighs  16  times  as  much,  a  litre  of  N  14  times  as 
much,  etc.,  according  to  the  atomic  iveight  of  the  gas.     To  find  the  weight 
of  compound  gases,  multiply  the  weight  of  H  by  one-half  the  molecular 
weight  of  the  gas.     Ex. — AJitre  of  C  0^  weighs  22  times  .0896  gms.] 

3.  Tell  what  you  know  about  0  (ten  lines). 

4.  Give  experiments  proving  the  character  (properties)  of  0. 

5.  Reaction  in  making  H? 

6.  How  many  litres  of  H  could  be  made  by  using  5  grams  of  Zn? 

7.  How  many  grams  of  Zn  must  be  used  to  make  15  litres  of  H? 


SULPHUR   AND   PHOSPHORUS,  79 


8.  Give  properties  of  H  and  prove  by  detailing  experiments. 

9.  What  is  a  deliquescent  salt?    An  efflorescent  salt? 

10.  How  was  N  obtained? 

11.  Give  the  composition  of  air 

12.  What  was  proved  by  the  "ammonia  fountain"? 

13.  What  is  "aqua  regia"?  and  why  so  called? 

14.  What  is  meant  by  "nascent"  hydrogen? 

15.  Give  experiment  proving  that  C  is  a  good  decolorizing  agent. 

16.  Give  experiment  showing  that  fresh  burned  C  is  good  "disinfect- 
ant " 

17.  How  may  C  O2  be  made? 

18.  Fifty  litres  of  C  02  could  be  made  by  using  what  quantity  (grams) 
of  Mg  C  03? 

19.  Detail  three  experiments  under  carbonic  oxide, 

20.  Animals  and  the  higher  orders  of  plants  differ  with  respect  to  use 
of  C  O,,  and  0.     How? 

21.  Write  o  lines  about  chlorine,  saying  the  most  possible. 

22.  How  is  glass  etched?     Copper  and  iron? 

23.  What  is  cyanogen?     Why  is  it  treated  in  the  chapter  on  chlorine, 
bromine,  etc.,  rather  than  under  nitrogen  or  carbon? 


CHAPTER     XXIII. 


SULPHUR    AND    PHOSPHORUS. 

Sulphur  is  found  free  (native)  in  volcanic  regions.  It 
is  found  combined  in  cinnabar  (Hg  S),  iron  pyrites  (Fe  Sa- 
iron  disulphide),  galena  (Pb  S),  blende  (Zn  S),  etc.  It  is 
contained  in  most  animal  tissues  and  especially  in  the 
perspiration  and  hair,  also  in  many  vegetables,  especially 
in  those  that  are  strong-smelling. 


80  CHEMICAL   PRIMER, 


EXP.  88. — Drop  a  well-cleaned  silver  coin  upon  yolk  of  egg  and  leave 
over  night.  It  is  blackened. 

Eggs  contain  sulphur  and  so  tarnish  silver  spoons,  black  silver  sulphide 
(Ag2S)  being  formed, 

EXP.  89. — Into  a  strong  solution  of  lead  acetate  introduce  white 
horse-hairs,  and  heat  to  hasten  reaction.  They  turn  dark. 

Many  "hair  dyes"  contain  salts  of  lead.  The  metal  unites  with  S  of 
the  hair,  forming  black  Pb  S.  Such  hair  dyes  are  highly  injurious 

Sulphur  exists  in  several  allotropic  (physically  different)  states,  among 
which  are  ( 1 )  the  crystallized,  (2)  the  common  uncrystallized  ("amor- 
phous"), and  (3)  the  plastic  (viscid,  also  uncrystallized). 

EXP.  90. — Heat  a  small  quantity  of  sulphur  for  about  five  minutes,  01 
till  the  thin,  light-colored  melted  mass,  after  becoming  dark  and  thick, 
becomes  thin  again.  Pour  by  thin  stream  into  cold  water.  Plastic  S 
results.  This  form  is  unstable  and  becomes  brittle  in  a  day  or  two,  as 
may  be  proved  by  examining  specimen  the  next  morning= 

EXP.  91.— In  a  small  glass  tube 
closed  at  one  end  (by  fusing  tip  in 
flame  of  Bunsen's  burner)  place  small 
piece  of  iron  pyrites  (Fe  S2)  and  heat 
slowly  so  as  not  to  crack  the  fused  end 
of  tube.  Part  of  the  sulphur  sublimes 
and  condenses  on  cold  part  of  the 


Fig.  32,  tube. 

3FeS2  Fe3S4    +     S, 

NOTE. — A  substance  sublimes  when,  on  applying  heat,  it  rises  as  a 
vapor  and  condenses  as  a  solid.  A  substance  distills  when  it  rises  as 
a  vapor  and  condenses  as  a  liquid. 

S  may  be  obtained  from  iron  pyrites  by  "roasting"  the 
ore  and  condensing  the  S.  The  principal  supply,  how- 
ever, comes  from  the  volcanic  regions  of  Italy.  (See 


EXP.  92.— Repeat  EXP.  4,  placing  in  the  bottle  a  red  rose.     The  rose 
is  slowly  bleached. 


/6-'vAi  '  **>*  H? 

.    rf    -A"^     ^-<5 
/ 


SULPHUR    AND   PHOSPHORUS.  81 


Sulphur  dioxide  is  used  in  bleaching  silk,  straw,  and 
woolen  goods,  which  would  be  injured  (turned  yellow)  by 
chlorine.  Colorless  compounds  are  formed  by  the  union 
of  the  S  O2  with  the  coloring  matter,  but  the  reaction  is 
too  complex  to  be  written  out. 

S  O2  is  also  an  antiseptic.  S  burned  in  a  vessel  pre- 
vents the  fermentation  Of  the  liquid  (as  new  cider)  after- 
wards put  in.  Like  all  strong  antiseptics  it  is  poisonous. 

EXP.  93.— Burn  S  in  a  large,  clean  flask  and  pass  into  it  H2S.  (See 
EXP.  8.)  Let  stand  a  few  hours— the  bottom  and  sides  of  the  flask  are 
covered  with  a  thin  white  coat  of  sulphur.  [S  looks  white  when  in  thin 
deposit.] 

S02     +     2  BUS     =     S3     -f-     2H,0 

This  illustrates  the  formation  of  native  sulphur  in  vol- 
canic regions,  as  volcanic  gases  contain  S  O2  and 


EXP.  94.— Bum  S  as  in  EXP.  4,  and  quickly  stir  with  glass  rod,  upon 
the  end  of  which  is  twine  wet  with  strong  H  X  03.  (Nitrates  are  good 
oxidiziny  agent-s,  we  have  learned. )  The  S  02  takes  0  from  the  nitric 
acid,  becoming  S  03  sulphuric  oxide  (anhydride).  Shake  up  with 
water. 

S  03    +     H20    =    H2S  04  (dilute) 

Test  water  with  barium  chloride,  the  test  of  sulphuric  acid  (and  solu- 
ble sulphates). 

H2S04     +     BaCl2     =    BaS04     +     2  H  Cl 

white  precipitate 

Sulphuric  acid  ("oil  of  vitriol")  is  a  colorless  (if  pure) 
oily  liquid  (sp.  gr.  1.84).  It  is  the  most  important  of  the 
acids,  and  is  used  in  preparing  numberless  other  sub- 
stances, especially  acids. 

The  experiment  illustrate*  its  preparation. 


-€ 


- 


82  CHEMICAL   PRIMER. 

S  02  from  burning  sulphur  is  carried  into  large  leaden  chambers, 
whose  floors  are  covered  with  water.  Into  these  air  and  nitric  acid 
fumes  are  admitted.  The  N  0  from  the  nitric  acid  acts  as  a  carrier  of 
0  from  the  air  to  the  S  02.  (See  EXP.  38.) 

/  / 

2  S  02     -f     N  A     =    2  S  O3    -f-  2N  0 

/ 
2NO      +     02    =    NA 

from 
the  air 

The  dilute  acid  is  evaporated  in  leaden  pans,  till  it  begins  to  attack 
the  lead.  (Commercial  H2S  04  contains  Pb  S  O4,  which  falls  as  white 
precipitate  when  the  acid  is  diluted. )  It  is  then  removed  and  concen- 
trated in  glans  or  platinum  stills. 

EXP.  95. — Into  a  beaker  containing  water  pour  twice  its  volume  of 
strong  H2S  04.  Great  heat  is  developed. 

EXP.  96.— Upon  white  sugar  (012H22On)  (starch  or  wood  C6H1005 ) 
pour  strong  sulphuric  acid.  It  chars  by  removing  the  elements  of  water, 
leaving  the  black  carbon  free. — Evaporate  dilute  H2S  04  upon  white 
paper.  As  the  acid  increases  in  strength,  the  paper  chars. 

Concentrated  sulphuric  acid  has  a  great  affinity  for 
water.  It  is  used  for  drying  gases  with  which  it  does  not 
react.  Care  must  be  taken  in  diluting  the  acid,  to  mix 
in  a  vessel  that  will  stand  the  heat.  (In  dilating  heavy 
liquids,  pour  the  liquid  into  the  water,  not  water  into  the 
liquid.)  "Fuming  sulphuric  acid"  is  a  solution  of  S  O3 
in  H2S  O_ 


EXP.  97.  —  Into  a  solution  (slightly  acidulated  with  H  Cl)  of  salts  of 
lead,  copper,  bismuth,  mercury  (io).  arsenicum,  antimony,  and  tin 
respectively  in  test-tubes,  put  solution  of  H..S.  Reaction  by  change  of 
partners  throws  down  sulphides.  Pb  S  black,  Cu  S  black,  Bi2S3  black, 
Hg  S  white,  yellow,  reddish-brown,  and  finally  black,  As2S3  lemon 
yellow,  Sb2S3  orange,  Sn  S  brownish-black,  Sn  S2  yellow. 

Hydrogen  sulphide  (H2S  "sulphuretted  hydrogen")  is 
much  used  in  the  laboratory  to  precipitate  metals,  as  sul- 
phides. (See  ANALYTICAL  CHARTS.)  H2S  is  readily  in- 
flammable, as  may  be  shown  by  igniting  in  test-tube. 


W^fo.Ajf 

'a/. 


SULPHUR    AND   PHOSPHORUS.  83 


NOTE. — Hydrogen  sulphide  has  a  slight 'acid  reaction  and  was  called 
by  the  old  chemists  hydrosulphiiric  add.  It  unites  with  many  of  the 
bases  to  form  sulphides,  and  these  sulphides  might  be  classed  as  binary 
salts.  For  reasons  which  need  not  be  explained  here,  chemists  do  not 
novv  class  sulphides  in  this  way,  but  consider  them  as  analogous  to 
oxides. 

Carbon  disulphide  (G  S2),  a  volatile,  colorless,  inflam-, 
mable  liquid,  may  be  produced  by  passing  sulphur  over 
red-hot  coals.  It  is  an  excellent  solvent,  dissolving  readily 
S,  P,  I,  and  many  organ^j  substances.  It  refracts  light 
powerfully,  and  hence  is  often  used  in  filling  prisms.  The 
impure  disulphide  (its  heavy  vapor)  is  used  to  poison 
squirrels,  insects,  etc. 

The  rare  element,  selenium,  in  many  respects  resembles  sulphur. 
We  have  the  compounds  H2Se,  Se  O^  H-^Se  04,  etc.  (See  SULPH-  AXD 
SELEX-SALTS.) 


Phosphorus  is  a  semi-transparent,  nearly  colorless, 
wax-like  solid.  It  is  kept  under  water  in  "sticks,"  as  it 
slowly  oxidizes  in  the  air  and  takes  fire  at  a  very  low 
temperature.  It  is  highly  poisonous.  Its  vapor  breathed 
(in  more  than  minute  quantities)  produces  ulceration  of 
the  jaw,  cured  with  difficulty.  (See  OAUTIOX,  EXP.  24.) 

Another  variety,  red  or  amorphous,  is  known.  This  differs  widely 
from  ordinary  P.  It  does  not  emit  the  "jaw-poisoning  fumes"  and  can 
be  safely  handled.  P  in  this  "allotropic"  state  maybe  prepared  by 
heating  ordinary  phosphorus  in  a  closed  vessel.  Part  of  the  P  used  in 
making  X  (Exp.  35)  is  changed  into  the  red  variety. 

Phosphorus,  because  of  its  low  igniting  point,  is  largely 
used  in  the  manufacture  of  matches.  The  wood  of  the 
match  is  first  dipped  in  melted  sulphur,  then  into  paste 
of  P,  potassium  nitrate  (or  chlorate)  for  an  oxidizing 

t  v    3,    <•  = 

f-i 


84 


CHEMICAL   PRIMER. 


agent  and  glue  (varnish).  The  P  is  kindling  for  the  S, 
the  S  for  the  wood  (hydrocarbon),  while  the  nitrate  fur- 
nishes the  O  for  rapid  combustion.  The  reactions  in 
burning  a  match  are:  — 


P2  +  05  =   P205; 
H,+  O      :  H20; 


S  +  02  ==   S02 
C  +  02  =  CO 


"  Safety  Matches"  contain  110  P,  and  ignite  readily  only  when  the 
chemicals  of  the  match  are  rubbed  on  a  surface  of  red  phosphorus  (and 
powdered  glass  to  increase  friction).  ( 

Phosphorus  glows  in  the  dark  (its  best  test).  (See  APPENDIX.  )  Such 
glowing  without  heat  is  called  phosphorescence,  but  not  by  any 
means  is  all  so-called  "phosphorescence"  produced  by  phosphorus. 

EXP.  98.— Into  a  test-tube  half  full  of  water  drop 
several  very  small  pieces  of  P.  Cover  P  with  fine 
crystals  of  K  Cl  03  (oxidizing  agent).  By  means 
of  a  pipette  (glass  tube)  take  up  a  little  strong 
H2  S  O4,  and,  introducing  the  tube  into  the  water 
as  deep  as  the  K  Cl  O3  (Fig.  33),  open,  letting  the 
strong  acid  upon  the  chlorate.  .  The  P  burns  be- 
neath  the  water. 

A  combustible  element  burns  if  raised  to  the 
igniting  point  in  presence  of  free  oxygen,  or  of  an 
oxidizing  agent.  (In  this  case  C12O4  from  the 
reaction. ) 

Calcium  phosphate  (Ca32  P  04)  forms  fully  one-half  by  weight  of 
bones,  and  is  the  source  of  P.  "Superphosphate  of  lime"  is  a  peculiar 
acid  phosphate  of  calcium  (Ca  H4  2  P  04). 

s> 


BORON  AND  SILICON.  85 


CHAPTKR    XXIV. 


BORON  AND  SILICON. 

Boron  may  be  obtained  from  boron  oxide  B2O3  as  a  brown  powder,  and 
also  in  yellowish-brown  crystals.  Boracif  acid,  or  boric  acid  (H3B  03), 
is  found  in  the  lagoons  of  the  volcanic  regions  of  Tuscany.  Jets  of 
steam  containing  the  acid  issue  from  the  earth  and  are  absorbed  by  the 
water.  This  is  afterward  ^vaporated  by  heat  from  the  jets,  leaving  the 
crystallized  acid.  Boracic  acid  is  also  made  from  borax. 

EXP.  99. — Upon  copper  (or  iron)  wire  covered  with  a  coating  of  the 
black  oxide,  melt  a  borax  bead.  The  melted  borax  dissolves  the  oxide, 
leaving  the  bright  "metallic"  copper  (or  iron). 

Borax  (sodium  tetraborate,  Na,  B4O7,  10H2  O)  is  used 
in  welding  and  soldering,  because  when  melted  it  dissolves 
the  oxide  of  the  metal,  leaving  the  surfaces  bright.  (See 
HARD  WATER.) 

EXP.  100. — Dissolve  boracic  acid  (or  borax  previously  moistened  by 
drop  of  dilute  sulphuric  acid,  to  liberate  boracic  acid)  in  a  little  alcohol 
(C^Hij  H  0)  and  ignite.  The  flame  has  a  peculiar  green  tint.  This  is  a 
good  test  for  the  presence  of  a  borate. 

EXP.  101. — Dissolve  copper  oxide  in  borax  bead  in  oxidizing  flame  of 
the  blowpipe.  Color  green  when  hot,  blue  when  cold.  Change  to  reduc- 
ing flame,  color,  reddish-yellow.  Dissolve  Mn  (X,  intense  reddish-violet 
in  oxidizing  flame,  in  reducing  flame  almost  colorless.  (See  BLOWPIPE, 
APPENDIX.) 

Borax  is  largely  used  in  blowpipe  analysis  as  a  "flux." 


Silicon  is,  next  to  O,  the  most  abundant  element, 
though,  unlike  O,  it.  is  always  found  combined  (not  free 
or  native).  The  larger  part  of  the  earth's  crust  is  silicon 


86 


CHEMICAL  PRIMER. 


oxide  (Si  O2  silica,  white  sand,  quartz), 
or  silicates.  Many  precious  stones 
(amethyst,  agate,  etc.)  are  quartz  col- 
ored with  some  metallic  oxide.  Sili- 
cates of  K  and  Na,  absorbed  by  roots, 
give  by  deposit  of  silica  the  stiffness 
and  shining  surface  to  corn-stocks  and 
the  edge  of  '•  sword  grass."  Quartz 
veins  often  "carry"  more  or  less  free 


Fig.  34.-Quart 


Petrifaction  is  the  replacement  of  wood  by  stone  (sil- 
ica). Silica  and  certain  silicates  are  soluble  in  water  con- 
taining alkaline  (K,  Na,  H^N)  carbonates.  As  fast  as 
the  wood  placed  in  the  water  decays,  the  silica  is  depos- 
ited, and  copies  very  precisely  the  lines  of  the  wood 
(knots,  grain,  etc.). 

is  a  mixture  of  several  silicates  (as  is  also  porce- 
lain). Crown  or  plate  glass  (common  window  glass)  is 
chiefly  calcium  and  sodium  silicates.  Ca  hardens  and 
gives  luster.  Na  makes  fusible,  but  gives  greenish  tint. 

Bohemian  glass  is  chiefly  calcium  and  potassium  sili- 
cates. Potassium  gives  no  color. 

Flint  glass  is  chiefly  K  and  Pb  silicates.  This  can  be 
ground  into  imitation  gems,  prisms,  etc.  When  very  rich 
in  lead  it  is  known  as  "paste." 

EXP.  102. — Into  a  piece  of  soft  glass  fuse  cobalt  oxide  (CoO),  the  piece 
is  colored  a  deep  blue. 

Glass  is  colored  any  desired  tint  by  fusing  with  a  small  quantity  of 
some  metallic  oxide.  "Purple  of  Cassius"  (which  see)  is  used  for  the 
finer  ruhy  red;  cuprous  oxide  also  colors  red;  cupric,  chromium,  and 
ferrous  oxides  give  green;  cobalt  oxide  gives  blue,  arsenous  oxide  the 
white,  soft  enamel  of  lamp  shades;  manganese  oxide  violet,  etc. 

Glass  is  annealed  by  being  cooled  very  gradually  for 

days.     When   cooled   quickly,  it  is  very  brittle.     Lamp 

•vwXw    ic- 


BORON  AND    SILICON.  87 

chimneys   break   from    sudden   change   of   temperature, 
because  not  properly  annealed. 

Glass  is  etched  .by  hydrofluoric  acid  as  we  have  seen 
in  EXP.  86. 

Pure  clay  (kaolin,  china  clay,  H.  A12  Si2  O8  +  H2  O) 
under  the  influence  of  heat  forms  a  hard,  porous  solid. 
Pure  feldspar  (K2  Na,  AL,  Si6  O16)  when  heated  fuses  to  a 
colorless  glass.  _Jf  china  clay  and  ground  feldspar  are 
heated  together,  the  fused  feldspar  penetrates  the  porous, 
infusible  clay,  producing  a  hard,  translucent,  lustrous 
mass — porcelain.  Besides  the  many  well-known  uses  of 
porcelain,  it  is  employed  in  the  laboratory,  as  it  resists 
the  action  of  acids  and  is  quite  refractory. 

Stoneware  differs  from  porcelain  in  opacity,  due  to  the 
fact  that  the  fused,  feldspathic  glass  does  not  penetrate 
the  entire  porous  mass  of  clay. 

In  common  earthenware  a  poorer  clay  is  used.  The  glaz- 
ing is  done  by  throwing  common  salt  (Na  Cl)  into  the  kiln 
when  the  burning  is  nearly  complete.  The  salt  volatilizes 
and  chemical  reactions  produce  sodium  aluminum  silicate, 
giving  a  glassy  surface. 

Common  pottery  ware  ("brown  earthen")  is  made  of 
the  most  impure  forms  of  clay,  usually  colored  reddish- 
brown  with  ferric  and  other  oxides.  It  is  often  glazed 
with  '"lead"  by  mixing  lead  oxide  or  galena  (Pb  S)  with 
the  clay. 

Silicates  (or  silica)  are  most  excellent  substances  to 
"make  hills  of,"  bejaus^  of  their  insolubility  and  hard- 
ness. Ev.flent'y  the  earth's  crust  could  not  be  made  of  sol- 
uble matter,  no,*  could  there  be  firm  continents  if  the  crust 
were  made  of  soft  material, 


88 


CHEMICAL   PRIMER. 


CHAPTER-  XXV 


ARSENICUM,   ANTIMONY,   AND   CHROMIUM. 

Arsenicum  (sp.  gr.  5.7)  is  a  brittle,  steel-gray  solid 
(semi-metal),  generally  found  in  combination.  Two  sul- 
phides, yellow,  As2S3  (arsenous  sulphide,  orpiment)  and 
red  As2S2  (realgar),  occur  native. 

Caution. — Care  must  be  taken  in  experimenting  with  arsenicum,  as 
itself  and  its  compounds  are  violently  poisonous.  Use  very  small  quan- 
tities in  all  experiments;  especially  avoid  breathing  H3As.  (See  ANTI- 
DOTES. ) 

EXP.  103. — Place  in  a  small  glass  tube,  closed  at  one  end  "white  arse- 
nic" (As203  arsenous  oxide  "ratsbane")  of  the  bulk  of  a  pin's  head. 
Hold  inclined  and  heat  very  gradually  (more  perfect  crystals  are  formed 
than  by  rapid  heating).  The  "arsenic"  sublimes  and  condenses  in 
minute,  octahedral  crystals  in  the  upper  and  colder  part  of  the  tube. 
(Examine  crystals  with  a  lens.) 

EXP.  104.— Perform  EXP.  103  in  a 
closed,  drawn-out  tube  (Fig.  35),  plac- 
ing above  the  arsenous  oxide  (anhy- 
dride) powdered  charcoal,  and  first 
raising  the  charcoal  to  low  red  heat. 
A  dark  mirror-like  ring  of  arsenicum 
condenses  upon  the  tube  above,  and 
a  garlic  odor  is  distinctly  perceived. 
[If  heating  is  too  rapid  the  carbon  is 
thrown  up  by  draft.  Though  not  so  sharply  defined,  the  arsenicum 
mirror,  in  case  of  this  accident,  is  readily  distinguished  from  the  char- 
coal.] 

Gt-o-...--  -  -^4....  4v    ,,     s~j  ^  ,  P 

1—  .-v  •    J  J 


S5- 


*  1 


ARSENICUM,  ANTIMONY,  AND  CHROMIUM.  89 


X 
•2  As,03     +     Cs     =     3  C  02     +     As, 

J&XF.  105.  —  Boil  a  few  decigrams  of  "white  arsenic"  in  water. 
As.203    -f-     3  H,0  2  H3As  03 

aoid-forming  water  hydrogen 

oxide  or  arsenite 

anhydride  (acid) 

Filter  and  preserve  filtrate  as  a  sample  of  an  arsenite.      (Of  course       i; 
this  may  be  considered  a  solution  of  arsenous  oxide  in  water.       (See 
EXP.  11.) 

EXP.  106.  —  Place  a  little  of  As203  of  the  bulk  of  a  pin's  head  in  ten 
drops  of  strong  H  N  O3,  and,  having  raised  to  the  boiling  point,  evapo- 
rate over  water-  bath  nearly  to  dryness.  Dilute  with  water,  filter  and 
preserve  as  an  example  of  an  arsenate, 

1.  As.203      +      O.,       =       As205 

arsenouB  from  nitric  aruenic 

oxide  acid,  an  oxide 

oxidizing 

agent 

2.  As.203     +     3  H,O     =     2  H3As  O, 

acid-forming  water  acid 

oxide 

EXP.  107.—  To  copper  sulphate  solution  (5  per  cent.)  add  H4N  H  O 
till  the  precipitate  formed  is  partially  but  not  wholly  dissolved.  Filter, 
divide  filtrate  into  two  portions.  To  the  first  add  drop  by  drop  an 
arsen&€,  a  yrten  precipitate  of  acid  copper  arsenite  (H  Cu  As  O3, 
"Scheele's  Green,"  Paris  green,  etc.  ,  used  as  a  pigment)  falls.  To  the 
second  portion  add  a  few  drops  of  an  arsenafc,  an  acid  copper  arsenate 
(H  Cu  As  O4)  bluish-green,  falls.  (See  ACID-SALTS.) 

EXP.  108.-  To  silver  nitrate  solution  (2i  per  cent.)  add  H4N  H  O  till 
precipitate  is  partially  but  not  wholly  dissolved.  Filter,  divide  filtrate 
into  two  portions  and  proceed  as  in  Exp.  107;  from  first  portion  yellov 
silver  arsenite  (Ag3AsO3)  falls;  from  the  second  portion  a  beautiful 
chocolate  silver  arsenate  (Ag3  As  O^)  falls.  Add  ammonium  hydrate  (or 
other  moderately  strong  alkaline  solution),  each  of  the  precipitates  dis- 
solve. 

By  the  last  experiment  an  arsenite  may  be  readily  dis- 
tinguished from  an  arsenate.  The  pupil  may  learn  here 
that  the  chemist  in  analysis  depends  largely  upon  the 
color  of  precipitates  and  solubility  (or  insolubility)  in 
various  reagents.  (See  EXPS.  109  and  111.) 

Arsenic  acid  is  used  in  preparing  aniline  red  (for  dyeing),  and  other 
iirsenates  (especially  Na3  As  04)  are  used  in  calico  printing. 


90 


CHEMICAL   PRIMER. 


Fig.  36. 


EXP.  109.— Into  a  small  flask  prepared  with 
safety-funnel  as  in  Fig.  36,  and  containing  Zn, 
pour  dilute  H2S  04  and  after  air  is  expelled  ignite 
as  with  philosopher's  lamp.  Pour  through  the  fun- 
nel a  few  drops  of  arsenical  solution  (ate  or  ite). 
The  color  of  the  flame  changes  and  the  cold  dish  is 
smutted  with  arsenicum.  (Just  as  a  candle-flame 
smuts  a  cold  dish  with  C.  The  arsenicum  of  the 
H3As  is  lowered  below  the  igniting  point,  while 
the  hydrogen  is  not. )  Upon  the  mirror-like  spot 
place  a  drop  of  calcium  chloride  solution  (or  of  hot 
strong  nitric  acid),  it  dissolves,  unlike  the  antimo- 
nial  spot.  (See  EXP.  111.) 


(1)— Zn     -f     H2S  04     =     Zn  S  O4     +     H2 
(2)— H3     +     As     =     H3As 

"nascent"  inflammable 

hyilrogeu  gas 

(3)— 2H3As     +     06     =     3H,0    +     As  A 

from 
air 

If  a  cold  test-tube  be  placed  over  without  touching  the  arsenical  flame, 
octahedral  and  characteristic  crystals  of  As203  and  moisture  condense 
upon  its  sides. 

NOTE.— Don't  breathe  the  gas  H3As.  The  experiment  should  be  per- 
formed under  a  gas  chimney  or  near  a  window  with  outward  draft.  If 
a  small  test-tube  ( without  safety -funnel)  is  taken  instead  of  the  flask, 
if  but  two  or  three  drops  of  As203  solution  is  used  and  the  apparatus 
held  at  arm's  length,  the  experiment  is  a  perfectly  safe  one  even  in  a 
closed  room.  This  is  stated  so  explicitly  because  a  few  teachers  are 
overcautious  and  omit  many  experiments,  while  on  the  other  hand  a 
few  are  culpably  careless. 

This  last  experiment  is  Marsh's  test  for  "  arsenic  "  (any 
compound  of  arsenicum).  Of  course  in  all  tests  the 
chemist  must  first  make  sure  that  his  materials  are  pure,  or 
at  least  free  from  the  substance  he  is  searching  for  in  the 
unknown  liquid  or  material.  (See  MAGNESIUM.) 

Arsenicum  (and  its  compounds)  is  a  powerful  antisep- 
tic. Bodies  of  those  poisoned  with  it  are  sometimes  pre- 


ARSENICUM,  ANTIMONY,  AND  CHROMIUM.  91 

served  from  putrefaction  for  years.  In  small  doses  it 
stimulates  and  causes  persons  to  grow  fat.  It  is  said  to 
beautify  the  complexion,  but  its  use  is  a  very  dangerous 
practice.  All  the  symptoms  of  arsenical  poisoning 
appear,  if  one  ceases  the  practice.  It  is  a  singular  fact 
that  in  a  certain  district  of  Hungary  the  peasants  habit- 
ually eat  "arsenic." 


Antimony  (sp.  gr.  6.7)  is  a  brittle,  highly  crystalline 

solid  (semi-metal),  with  brilliant  luster.  Upon  the  surface 
of  its  bluish-white  masses  are  usually  fern-like  crystalli- 
zations. 

EXP.  110. — Into  an  acidulated  (H  Cl)  dilute  solution  of  antimony 
v  (tirtar  emetic,  K  Sb  0  C4H406,  potassium  "antimony!"  tartrate)  pass 
H2S  gas  (or  its  solution).       Sb2S3,  antimonous  sulphide,  orange-yellow, 
falls.     Filter,  dry,  and  heat  carefully;  it  turns  grayish-black. 

Native  antimonoiis  sulphide  (gray  antimony,  or  antimony  glance) 
is  the  source  of  the  Sb  of  commerce. 

EXP.  111.— Perform  EXP.  109,  using  antimonial  solution  instead  of 
arsenical.  Dark  antimony  spots  are  obtained.  Upon  one  place  solu- 
tion of  calcium  chloride,  it  is  unaffected;  upon  another  place  a  drop  of 
hot  nitric  acid,  it  is  oxidized  (turned  white,  Sb.jOs),  but  not  dissolved. 
(See  Remarks,  EXP.  108.) 

Antimony  is  a  constituent  of  several  important  alloys, 
as  type  metal,  etc.  (See  ALLOYS.) 

An  alloy  is  a  mechanical  mixture  of  two  or  more 
metals  (including  semi-rnetals).  If  one  of  the  metals  is 
mercury,  the  alloy  is  called  an  amalgam.  A  mechanical 
mixture  differs  from  a  chemical  compound  in  that  it  may 
contain  its  constituents  in  any  proportions,  but  a  chemi- 
cal compound  must  contain  each  constituent  in  some  one 
proportion,  or  multiple  of  that  proportion. 

" 


92  CHEMICAL   PRIMER. 

Chromium  (sp.  gr.  4.8)  is  a  silver- white  metal  (considered  a  metal, 
though  ordinarily  negative  to  H).  (Let  the  student  learn  right  here 
that  the  order  of  elements  in  Table  No.  1  is  the  usual  order.  Rarely  an 
element  takes  a  different  position  when  obtained  by  electrolysis  under 
different  circumstances,  or  from  different  compounds.) 

Chromium  makes  both  acid-forming  (Cr  03)  and  basic  (Cr203)  oxides 
with  corresponding  acid  (H2Cr  O4  chromic  acid)  and  base  (Cr2  6  H  0) 
respectively. 

The  principal  ore  of  chromium  is  "chromic  iron  ore"  (Fe  Cr2  04). 
A  few  of  its  compounds  are  extensively  used  in  the  arts,  viz. :  potassium 
chromate  (K2Cr04),  potassium  bichromate  (di-)  (K2Cr207),and  lead  chro- 
mate  (Pb  Cr  04)  "chrome  yellow."  (See  AXA.  CHARTS.) 

/  A/V   >  &&^Lx»  .       /tiA*7>J    f''     f  -f-    *  tT*'  V^O     (*P 

r  I  A  ' 


CHAPTBR     XXVI, 


GOLD    AND     PLATINUM. 

NOTE. — With  this  chapter  we  begin  the  study  of  the  metals  proper. 
In  general,  a  metal  is  an  elementary  substance  (1)  with  a  peculiar 
luster,  called  metallic,  (2)  insoluble  in  water,  (3)  a  good  conductor  of 
heat  and  electricity,  (4)  positive,  with  reference  to  hydrogen,  and  (5) 
uniting  with  H  and  0  to  form  bases.  Chemists  are  not,  however, 
agreed  as  to  any  precise  definition,  and  the  line  between  metals  and 
non-metals  cannot  be  sharply  drawn.  This  is  the  case  with  terms  used 
in  all  sciences  (except  in  the  exact  sciences,  included  in  the  general  term 
mathematics).  No  line  can  be  drawn  between  soluble  and  insoluble 
substances,  for  one  kind  fades  gradually  into  the  other.  For  example, 
Pb  is  considered  insoluble,  but  traces  of  the  metal  may  be  found  in  dis- 
tilled water  that  has  been  in  a  leaden  dish  for  a  day  or  two.  It  oxid- 
izes and  dissolves.  No  line  can  be  definitely  drawn  between  "hot" 
substances  and  "cold"  ones,  but  the  terms  are  relative.  The  same  is 
true  of  poisonous  and  non-poisonous  substances. 

In  the  arts  an  alloy  of  two  or  more  metals  is  often  spoken  of  as  "the 
metal,"  but  this  is  a  technical  and  loose  use  of  the  term. 


GOLD   AND   PLATINUM.  93 

For  uses  of  the  metals,  reduction  of  their  ores,  etc.,  see  fuller  accounts 
in  the  cyclopaedia  and  in  larger  works  on  chemistiy.  See  also  APPENDIX. 

Gold  (sp.  gr.  19.3,  fusing  point  1,100°)  is  found  native 
(free),  frequently  alloyed  with  silver,  in  quartz  veins,  allu- 
vial deposits  (''placers"),  etc.  It  is  obtained  by  (1) 
quartz  mining,  (2)  placer  mining,  and  (3)  hydraulic 
mining. 

EXP.  112.— Dissolve  a  piece  of  gold-leaf  in  globule  of  Hg.  Place  the 
amalgam  on  hard  glass  and  in  window  with  outward  draft;  keep  at  dull 
red  heat  for  a  little  time.  Hg  distills  leaving  the  gold. 

Mercury  is  used  to  extract  gold  from  the  sands  or  from 
pulverized  quartz.  The  amalgam  of  Au  and  Hg  is  then 
submitted  to  pressure  in  "bags,"  which  squeezes  out  much 
of  the  Hg.  The  remainder  is  driven  off  by  distillation, 
but  the  Hg  is  saved,  not  thrown  away  as  in  the  experi- 
ment. 

Gold  is  a  very  brilliant  orange-yellow  solid,  the  most 
ductile  and  malleable  of  the  metals  (280,000  sheets  of  the 
finest  gold-leaf  make  only  one  inch  in  thickness).  It  was 
known  as  the  "king  of  metals,"  and  together  with  plati- 
num and  silver  (also  rare  metals  of  platinum  group)  is 
called  a  noble  metal.  The  others  in  contrast  are  called 
base  metals.  It  is  insoluble  in  any  of  the  common  acids, 
but  dissolves  in  "aqua  regia,"  chlorine-water,  or  bro- 
mine-water. 

Pure  gold  is  too  soft  for  jewelry,  coin,  etc.,  and  is  hardened  by  cop- 
per. A  carat  is  ^.  An  alloy  containing  -|-J  pure  gold  is  said  to  be 
gold  of  16  carats  fine. 

Aurous  cyanide  (Au  C  N)  dissolved  in  solution  of  K  C  X  is  used  in 
electro-gilding.  The  clean  substance  to  be  plated  is  hung  upon  the  neg- 
ative pole  of  the  battery  and  gold  upon  the  positive  pole. 

• 

^ri 


94  CHEMICAL   PRIMER. 

Platinum  (sp.  gr.  21.5,  fas.  pt.  2,000°)  is  found  native, 
usually  alloyed  ("platinum  ore")  with  iron,  copper,  or  some 
of  the  rare  metals  (palladium  used  to  color  "salmon" 
bronze,  rhodium,  iridium  used  to  tip  gold  pens,  ruthe- 
nium and  osmium)  of  the  platinum  group.  Like  gold, 
it  is  insoluble  in  any  one  of  the  common  acids,  but  dis- 
solves in  chlorine-water,  and  slowly  in  aqua  regia 
(H  01  -f-  H  N  O3).  Its  "ore"  is  worked  by  means  of  the 
oxy-hydrogen  blowpipe,  coal  gas  being  usually  used  in 
place  of  H. 

Platinum  —  because  of  its  high  fusing  point  and  its  insolubility  in 
most  liquids  —  is  to  the  chemist  an  exceedingly  useful  metal.  From  it 
he  makes  crucibles,  stills  (see  HJ3  04),  wire,  blowpipe  tips,  etc. 

I  f     fl     ^L_^  f-~\ 

' 


CHAPTER    XXVII. 


SILVER,    MERCURY,    AND    LEAD. 

Silver  (sp.gr.  10.5,  fiu.  pt.  1,040°)  is  found  native,  often 
alloyed  with  copper,  mercury,  and  gold.  Ag2S  (mixed 
with  other  sulphides,  as  galena,  Pb  S)  and  Ag  Cl  ("horn 
silver")  are  among  its  chief  ores. 

EXP.  113. — Repeat  EXP.  6  and  place  the  resulting  Ag  Cl,  mixed  with 
a  little  K2C  03  (or  Na2C  03)  upon  charcoal  and  heat  in  reducing  flame 
of  the  blowpipe.  A  silver  globule  ("button")  is  obtained. 

(1)-K2C03     +     2AgCl    —    Ag2C03     +     2KC1 

(2)-Ag,COs     =     Ag,0     +     CO. 
(3)-2AgaO     -f     C     =    Ag,     +     CO, 

deoxidizing 
age  lit 

<8&f  *M*  *i  &f^' 

Of  & 

***•      ^      $H 


SILVER,  MERCURY,  AND   LEAD.  95 


The  melted  globule  absorbs  oxygen  from  the  air,  and  if  cooled  quickly 
the  escaping  0  breaks  the  hardening  surface,  and  the  melted  ("molten") 
silver  runs  outx(  "spitting"  or  "sprouting"). 

Silver  is  a  brilliant  white  metal.  For  jewelry,  coin, 
etc.,  it  is  hardened  with  Cu.  It  is  used  for  silvering  mir- 
rors because  it  takes  a  high  polish.  It  is  not  acted  upon 
by  fused  caustic  alkalies  (K  H  O,  Na  H  O,  etc.),  as  glass 
and  platinum  are,  and  hence  certain  chemical  vessels  are 
made  from  the  metal.  It  expands  at  the  moment  of  solid- 
ification and  hence  can  be  cast  (copies  fine  lines  of  the 
mould). 

Silver  is  obtained  from  the  sulphide  by  (1)  roasting  the  pulverized 
ore  with  salt,  Ag.2S  -f  2  Na  Cl  =  2  Ag  Cl  -f-  Na2S,  and  (2)  by  placing 
the  Ag  Cl  in  a  cylinder  with  H^O,  Hg  and  Fe  scraps,  2  Ag  Cl  -f  Fe  — 
Fe  CL  -f"  -A-oa-  The  Hg  forms  an  amalgam  with  silver  from  which  the 
Ag  is  obtained,  as  gold  is  obtained  from  gold  amalgam.  The  process 
of  EXP.  113  is  too  expensive  for  the  practical  miner,  though  used  by  the 
assayer. 

Silver  may  be  freed  from  lead  by  f  losing  the  alloy,  and  as  Pb  crys- 
tallizes first  it  may  be  skimmed  out.  This  leaves  a  portion  of  the  Pb, 
which  may  be  completely  extracted  by  cnpellation.  (A  cupel  is  a 
shallow  dish  made  of  bone  ashes. )  The  Ag  containing  Pb  and  other 
impurities  is  placed  in  the  cupel  and  raised  to  the  red  heat.  A  hot  cur- 
rent of  air  plays  upon  the  fused  mass.  The  Pb  is  oxidized  and  the  Pb  O 
is  absorbed  by  the  cupel.  After  a  while  the  refiner  sees  the  mirror-like 
globule  of  pure  silver  and  quickly  removes  it,  lest  it  also  oxidize  and 
waste. 

Silver  nitrate  (Ag  X  03,  lunar  caustic)  is  the  most  important  salt 
of  silver.  It  forms  with  organic  compounds  by  the  action  of  light  a 
very  stable,  dark  compound,  and  hence  is  used  in  indelible  inks. 
Hair  dyes  sometimes  contain  it,  but  these  are  highly  injurious. 

The  changes  which  the  salts  of  silver  undergo  when  exposed  to  light, 
especially  in  presence  of  organic  matter, /is  the  basis  of  photogra- 
phy. (See  EXP.  6,  NOTE.) 

- 

EXP.  114. — Borrow  an  old  "negative"  from  a  photographer,  and  upon 
a  sheet  of  prepared  paper  (moistened  with  silver  salt  and  dried  in  the 


CHEMICAL  PRIMER. 


dark)  furnished  by  him,  print  by  means  of  a  few  moments'  exposure  to 
direct  sunlight,  a  photograph.  After  removal  and  a  few  hours'  exposure 
(even  to  reflected  light),  the  picture  fades  out,  because  the  entire  paper 
turns  black. 

The  photographer  applies  reagents  to  dissolve  from  the  unblackened 
portion  the  silver  salt,  and  thus  preserves  the  picture.  In  preparing 
the  negative  he  first  covers  the  glass  with  an  organic  film  (collodion)  to 
receive  the  silver  salts.  (Hold  a  lens  up  between  the  window  and  a 
sheet  of  paper.  The  lens  converges  the  rays  of  light  and  forms  an  in- 
verted image  of  the  window  upon  the  paper.  This  explains  the  forma- 
tion of  the  "negative"  in  the  dark  "camera.")  After  the  formation  of 
the  image,  he  treats  the  slide  (glass)  with  reagents  whose  action  upon 
the  part  previously  influenced  by  the  light  is  different  from  their  action 
upon  the  part  uninfluenced  by  the  light.  The  silver  salts  upon  the  un- 
blackened portion  are  dissolved  and  the  blackened  portion  is  "fixed" 
so  that  his  picture  does  not  fade  out  like  ours.  But  the  simple  princi- 
ple of  photography  should  be  learned  here,  not  the  art.  (See  APPENDIX.  ) 

A  solution  of  Ag  C  N  in  solution  of  K  C  N  is  used  in  electroplating. 
The  clean  substance  to  be  plated  is  hung  upon  the  negative  pole,  and 
silver  upon  the  positive. 


Mercury  or  "quicksilver"  (sp.  gr.  13.5,  fus.  pt.,  i.  e., 
freezing  point — 39.4°)  is  found  native  in  small  quantities, 
but  its  chief  source  is  the  ore  cinnabar  (Hg  S  mercuric 
sulphide)  from  which  the  liquid  metal  is  obtained  by  mix- 
ing with  iron  turnings  (or  lime)  and  distilling. 

Hg  S     +'    Fe     =     Fe  S     -f     Hg 

When  Hg  S  is  prepared  artificially  (by  "subliming"  together  S  and 
Hg)  it  is  called  vermilion  and  is  used  as  a  pigment. 

Mercury  is  largely  used  in  making  thermometers,  ba- 
rometers, etc.,  for  collecting  gases  soluble  in  water  (see 
FlG.  24),  for  extracting  gold  and  silver  from  their  ores, 
for  silvering  mirrors  (tin  amalgam),  and  formerly  was 
much  more  used  in  medicine  than  now. 


SILVER,  MERCURY,  AND  LEAD.  97 

"Blue  pill"  is  Hg  "rubbed  up"  with  confection  of  roses 
till  the  globules  are  not  visible  to  the  naked  eye.  Blue 
ointment  is  mercury  "rubbed  up"  with  lard. 

EXP.  115. — Pour  a  little  dilute  nitric  acid  upon  a  considerable  quan- 
tity of  Hg,  and,  bringing  to  boiling  point,  leave  over  night;  pour  off 
from  the  excess  of  Hg  and  preserve  as  solution  of  mercunws  nitrate 
(Hg22  X  O3).  Dissolve  a  small  globule  of  Hg  completely  in  an  excess  of 
hot,  strong  nitric  acid.  Evaporate  nearly  to  dryness,  dilute  and  pre- 
serve as  solution  of  mercuric  nitrate  (Hg  2  X  03).  (Of  course  these  salts 
may  be  obtained  dry  by  evaporation  over  a  water-bath. ) 

EXP.  116. — To  a  solution  of  mercurous  nitrate  add  H  Cl. 

Hg:42N03    +    2HC1    =    Hg2Cl2    -f    2  H  N  O3 

white 
precipitate 

Mercurous  chloride  (calomel,  Hg2Cl,)  is  an  insoluble 
(in  water)  white  powder.  It  acts  powerfully  upon  the 
glandular  system  (liver,  etc.),  and  in  large  or  long  contin- 
ued doses  produces  salivation  (excessive  action  of  the  sal- 
ivary glands)  and  other  serious  results.  It  was  formerly 
used  in  medicine  much  more  than  now,  by  some  almost 
as  a  "cure  all." 

EXP.  117. — To  a  solution  of  mercuric  nitrate  add  H  Cl. 

Hg  2  N  03    +    2  H  Cl    =    Hg  Cl,    +    2  H  N  O3 

There  is  no  precipitate  because  Hg  C12  is  soluble.  Place  one  drop  of 
the  solution  on  clean  glass  and  evaporate  at  low  heat.  White  crystals 
of  Hg  C12  are  obtained. 

Mercuric  chloride  (Hg  C12  corrosive  sublimate)  is  a 

powerful  poison  and  a  strong  antiseptic.  It  is  used  to 
prevent  the  decay  of  wood,  and  its  dilute  solution  in  alco- 
hol brushed  over  specimens  in  Natural  History  preserves 
them.  (See  ANTIDOTES.) 


> 


98  CHEMICAL  PRIMER. 

Lead  (sp.  gr.  11.4,  fus.  pt.  334°)  is  rarely  found  free. 
Its  chief  ore  is  lead  sulphide  (Pb  S,  galena),  often  carrying 
Ag2S.  The  roasting  ("smelting")  of  this  ore  and  separa- 
tion of  the  metal  is  a  very  simple  process.  Pb  is  soft  and 
malleable,  and  when  fresh  cut  has  a  lustrous  bluish-gray 
color,  quickly  dulled  by  oxidation.  Its  common  uses  are 
well  known  to  every  school-boy.  It  contracts  in  solidify- 
ing, and  hence  will  not  make  accurate  castings  (i.  e.,  will 
not  copy  the  fine  lines  of  the  mould). 

EXP.  118. — Make  two  moulds  by  boring  conical  cavities  into  plaster 
of  Paris  (Ca  S  04,  2  H2  0)  and  making  fine,  clean-cut  grooves  on  the 
sides.  Into  one  pour  pure  melte'd  lead.  Into  the  other  pour  melted 
lead,  in  which  a  little  Sb  and  Sn  has  been  previously  dissolved  (type 
metal).  The  first  casting  is  blunt  and  does  not  copy  the  grooves;  the 
second  is  sharp,  pointed,  and  copies  the  grooves  accurately.  This  is 
caused  by  expansion  of  the  crystalline  Sb  and  Sn  in  solidifying.  [Sb 
alone  may  be  used  as  well.] 

Water  used  for  drinking  purposes  should  not  be  brought 
great  distances  in  lead  pipes  (unless  the  water  contains 
considerable  quantities  of  phosphates,  carbonates,  or  sul- 
phates, which  coat  the  lead  with  white  coat),  and  water 
that  has  stood  over  night  in  the  short  lead  pipe  connect- 
ing with  faucet  should  be  allowed  to  run  out  before  drink- 
ing. Water  containing  even  minute  quantities  (and 
otherwise  practically  harmless)  of  ammoniacal  salts  (from 
decomposition  of  organic  matter)  dissolves  lead  and  keeps 
the  surface  bright.  Chronic  lead  poisoning  is  produced 
by  drinking  such  water.  Lead  is  an  "accumulative" 
poison,  i.  e.,  it  remains  in  the  system  and  is  thrown  off 
with  difficulty.  Painters  are  often  attacked  by  "colic" 
produced  by  lead  poisoning. 

Fruit  cans  should  not  be  soldered  with  an  alloy  of  Pb.  (See  EXP.  120 
and  connection.)  Metallic  Pb  is  not  poisonous  because  of  its  insolubil- 
ity. (Plumbers  are  not  attacked  by  "lead  colic.") 


SILVER,  MERCURY,  AND   LEAD. 


99 


Litharge  (Pb  0)  (see  EXP.  50)— "red  lead"  (Pb3  0,)— " sugar  of 
lead  "  (lead  acetate  Pb  2  C,  H:<  02).  and  "  white  lead  "  chiefly  (Pb  C  03 
but  containing  a  little  Pb  2  H  0)  used  in  painting,  are  important  com- 
_^ ^ H^ MHM MB  pounds.  All  are  poisonous,  especially  the 
very  soluble  acetate.  (See  ANTIDOTES,  also 
EXP.  12.) 

White  lead  is  made  as  represented  in 
Fig.  37.  A  roll  of  lead  (B)  is  placed  in  an 
earthen  vessel,  and  below,  weak  vinegar  (A). 
Above  (and  around)  is  packed  decaying  tan- 
bark  (C)  and  refuse.  These  vessels  are 
arranged  in  immense  piles;  the  heat  of  the 
decomposition  assists  the  evaporation  of  the 
vinegar,  and  in  five  or  six  weeks  the  lead  is 
all  converted  into  Pb  C  03. 


Fig.  37. 


Pb    +    0    +     HC2H302 

from  from 

Air  vinegar 

CO,    +     PbHOC2H,O,    = 

from  decomposing  basic  lead 

refuse  acetate 

(see  basic  salts) 


=     PbHOC.,H,0, 


PbC03 

"white 
lead" 


HC2H,02 

unites  with 

another  portion 

of  Pb 


White  lead  is  often  largely  adulterated  with  gypsum  (Ca  S  04  2  H20) 
heavy  spar  (Ba  S  04),  etc.  Pure  Pb  C  03  dissolves  completely  in  hot 
dilute  H  X  03,  and  the  adulteration  is  easily  detected. 

EXP.  119.— Add  a  little  mucilage  to  lead  acetate  solution  (sympathetic 
ink)  and  write  with  fine  hand  a  few  words.  Dry;  they  are  invisible. 
Moisten  the  paper  and  allow  H2S  gas  to  come  in  contact  with  it.  The 
letters  become  black.  (See  EXP.  9. ) 

H2S  is  a  test  for  lead,  and,  vice  versa,  lead  acetate  (paper  moistened  with 
it)  is  a  test  for  H2S.  "A  body  acted  upon  characteristically  by  a  reagent  is 
as  qood  a  test  for  tfie  reagent  a*  the  reagent  is/or  it." — Attfald.  (Sea  test 
iii  AXA.  CHARTS.) 


tOO  CHEMICAL   PRIMER. 


CHAPTER    XXVIII 


Cu,  Fe,  Zn,  and   Sn. 

Copper  (sp.  gr.  8.9,  fus.  pt.  1,200°)  is  found  free  in  large 
masses  (Lake  Superior  mines).  Its  most  common  ore  is 
copper  pyrites  (Fe  Cu  S2),  from  which  it  is  obtained  by 
roasting  with  a  silicate,  or  with  silica  (Si  O.2),  to  remove 
the  iron  as  iron  silicate,  and  again  roasting  the  Cu  S.  It 
is  a  reddish  metal,  highly  malleable  and  ductile.  With 
the  exception  of  Ag  it  is  the  best  conductor  of  heat  and 
electricity.  Brass,  bronze,  and  bell-metal  contain  Cu. 
(See  ALLOYS.) 

The  salts  of  copper  are  poisonous.  (See  ANTIDOTES.) 
Substances  containing  acids  (fruits,  jellies,  pickles,  etc.) 
should  never  be  put  in  copper  (or  brass)  utensils.  Fats 
dissolve  copper  oxide,  and  therefore  should  be  put  into 
copper  dishes  only  when  the  vessels  are  bright.  Copper 
sulphate  ("blue  vitriol,"  "blue  stone"  Cu  S  O4  5  H2O)  is 
used  in  calico  printing  and  in  galvanic  batteries.  (See 
EXP.  34.)  The  native  malachite  (Cu  C  O3  +  Cu  2  H  O) 
takes  a  high  polish  and  is  used  for  jewelry  and  other 
ornamental  articles.  Verdigris  is  copper  acetate 
(Cu  2  C2  H3  O2)  though  the  name  is  often  applied  to  the 
artificial  carbonate. 


Cw,  Fe,  Zn,  and  Sn.  101 


Iron  (sp.  gr.  7.8,  fus.  pt.  1,000°  to  1,800°)  is  the  most 
important  of  all  the  metals.  It  is  rarely  found  free 
(always  found  free  in  aerolites)  but  in  combination  it  is 
widely  distributed,  traces  being  found  in  the  blood  of  ani- 
mals and  in  the  juices  of  plants.  It  is  a  soft,  silver- white 
metal  (if  pure).  Among  the  most  important  of  its 
numerous  ores  are  Fe^O3  ("specular  iron"  hematite) — 
Fe2  6  H  O  -f  Fe2  O3  (brown  hematite,  limonite) — Fe3  O< 
("magnetic  iron"),  and  Fe  C  O3  (spathic  iron,  ferrous  car- 
bonate). The  value  of  the  ore  depends  as  much  upon  the 
nature  of  its  impurities  as  upon  the  percentage  of  iron. 

The  old  process  of  reduction  ("Direct  Process")  was  to  roast  the  ore 
with  charcoal  in  an  open  "forge"  fire.  The  pasty  mass  of  reduced  iron, 
called  "bloom"  separates  from  the  fused  silicates  (or  fused  glass),  called 
"slag." 

The  modern  process  ("Indirect")  consists  of  two  parts,  (1)  obtaining 
the  reduced  iron  from  the  ore,  not  pure,  but  containing  a  large  percent- 
age of  C.  (This  is  cast  iron,  or  "pig  iron.")  (2)  The  production  of 
iron  nearly  free  from  C  ("wrought  iron")  from  the  cast  iron. 

1.  The  ore  is  placed  in  a  "blast  furnace"  with  layers  of  coal,  coke, 
and  "flux"  [the   last,  limestone  Ca  C  O3,  if  impurities    are  silicates 
(clayey),  and  silicates,  if  the  impurities  are  calcareous.      Of  course,  the 
object  is  to  form  a  "slag"  of  calcium  glass].    Hot  air  is  driven  in  below. 
The  heat  of  the  furnace  is  intense  and  its  action  continuous.    The  "life" 
of  the  furnace  fire  is  often  twenty  years,  fresh  material  being  ceaselessly 
supplied  from  above.      The  melted  iron  and  "slag"  (floating  on  iron)  is 
drawn  off    below.      [The  hot  C  O2  and  unburnt  gases    passing  from 
chimney  are  utilized  for  heating  the  air  driven  in  below.]      The  iron 
runs  into  a  large  main,  called  "sow,"  and  thence  into  lateral  moulds 
called  "pigs"  (hence  "pig  iron"). 

2.  Pig  iron  (2  to  5  per  cent,  of  C)  is  changed  to  wrought  iron  (less 
than  \  per  cent,  of  C)  by  burning  out  the  C  (also  S,  Si,  and  P)  in  a 
reverberatorv  furnace,  "puddling  furnace"  (Fig.  38).     Fuel  burns  upon 
the  grate  A;  pig  iron  is  placed  upon  the  floor  B,  and  is  frequently  stirred 
by  means  of  openings  in  the  side. 


102 


CHEMICAL   PRIMER. 


Fig.  38. 

Steel  contains  more  C  than  wrought  iron  and  less  than 
cast  iron.  It  may  be  made  by  heating  bars  of  wrought 
iron  to  redness  in  contact  with  powdered  charcoal  for  eight 
or  ten  days.  This  is  called  the  cementati  n  process. 

Bessemer  steel  is  made  by  decarbonizing  the  best  pig 
iron  (free  from  phosphorus  and  sulphur)  at  a  fearful  heat 
in  an  egg-shaped  vessel  (-' converter"}  lined  with  infusible 
material.  Hot  air  is  driven  in  below  through  numerous 
openings  by  means  of  a  powerful  engine.  Si  is  also  re- 
moved. "Looking-glass"  iron  containing  a  known  quan- 
tity of  C  and  a  little  Mn  is  then  added.  Bessemer's  proc- 
ess is  a  rapid  one.  Bessemer  steel  is  largely  used  in 
constructing  railroads,  bridges,  etc. 

Steel  expands  at  the  moment  of  solidification  and  there- 
fore can  be  cast.  Few  metals  besides  iron  can  be  welded. 
(To  be  welded  a  metal  must  soften  before  melting.) 
Cast  iron  cannot  be  welded.  Iron  (or  its  salts)  is  largely 
used  in  medicine  as  a  tonic. 

Ferrous  sulphate  (Fe  S  04,  7  H20,  green  vitriol,  copperas)  is  used 
in  dyeing,  making  ink,  etc.  Fe  S  is  used  in  preparing  the  reagent  H28 
(Exp.  8).  Iron  disulphide  (Fe  S2,  iron  pyrites,  "fool's gold")  may  be 
readily  distinguished  from  gold  by  heating  and  observing  the  odor  of 
S  02  and  also  the  change  in  color.  (See  EXP.  91.) 


Cu,  Fe,  Zn,  and  Sn.  103 


Zinc  (sp.  gr.  6.9,  fus.  pt.  410°)  very  rarely  occurs- native. 
Its  chief  ores  are  Zn  C  O3  ( smithsonite ),  Zn  S  (zinc 
blende),  and  Zn  O  ("red  zinc  ore"  colored  red  by  an  oxide 
of  Mn).  It  is  a  bluish-white  crystalline  metal.  Fe  dipped 
in  melted  Zn  is  coated  with  the  metal  and  forms  what  is 
termed  galvanized  iron.  Water  that  has  stood  a  long 
time  in  zinc-lined  vessels  (tanks)  is  unfit  to  drink.  Zn  O 
(zinc  white)  is  used  as  paint.  (See  ALLOYS.) 


Tin  (sp.  gr.  7.3,  fus.  pt.  230°)  is  obtained  from  its  prin- 
cipal ore  Sn  O.,  (tin  dioxide,  stannic  oxide,  "tin  stone") 
by  roasting  with  carbon  in  reverberatory  furnace.  It  is 
a  lustrous,  white,  highly  crystalline  metal,  malleable  and 
ductile.  When  a  bar  of  tin  is  bent,  a  crackling  sound 
("tin  cry"),  caused  by  the  friction  among  the  crystals,  is 
heard. 

"Tinware"  is  really  iron  ware  coated  with  Sn  (by 
dipping  the  iron  into  melted  tin).  When  the  tin  wears  off, 
the  iron  rust  (Fe2O3,  or  hydrated  Fe,  6  H  O)  is  seen.  Tin 
is  often  adulterated  with  (the  cheaper)  lead.  Fruit  con- 
tained in  cans  coated  with  such  "tin"  is  unfit  to  eat,  for 
it  contains  poisonous  lead  salts.  Solder  for  such  cans 
should  contain  no  lead.  Pb  is  easily  detected  by 

EXP.  120. — Upon  a  piece  of  "tin"  (tinned  iron)  place  a  drop  of 
H  X  03  and  evaporate  to  dryness.  Add  a  drop  of  K  I  solution,  yellow 
Pb  I.2  is  formed  if  lead  is  present.  [Try  the  experiment  with  a  piece 
of  "tin"  upon  which  a  minute  piece  of  lead  has  been  melted,  forming 
alloy.] 

Pb2X03    +    2KI    =    2KN03    -f     Pb  Is 

yellow 

Pins  made  of  brass  wire,  copper  utensils,  iron  tacks,  etc. ,  are  often 
covered  with  a  thin  coat  of  tin  to  give  bright  surface.  Tin  is  largely 
used  in.  making  alloys  (which  see). 

Tin  disulphide  (Sn  S2),  a  bright  golden-yellow,  is  known  as  mosaic 
gold,  and  is  used  in  decorative  painting.  Sn  C12  (stannous  chloride) 
and  Sn  C14  (ic)  are  largely  used  in  dyeing. 


104  CHEMICAL   PRIMER. 


CHAPTER    XXIX. 


Bi,  Co,  Ni,  Mn,  Al,  and  Mg. 

Bismuth  (sp.  gr.  9.8,  fus.  pt.  264°)  is  a  brittle,  purplish- 
white,  crystalline  metal.  It  forms  alloys  with  other  met- 
als, expanding  much  in  solidifying  and  remarkable  for 
their  low  melting  point 

EXP.  121.— Fuse  Bi  (5  dcg.),  Pb  (3  dcg.),  and  Sn  (2  dcg.)  together. 
The  alloy  is  fusible  metal  (one  variety).  Place  the  cold  globule  in 
water  and  raise  to  the  boiling  point.  Notice  that  the  alloy  melts  (at 
91.6°)  before  the  water  boils. 

Fusible  metal  is  used  for  taking  casts  of  wood  cuts,  etc.  Fusible 
metal  (of  different  composition  and  melting  at  some  definite  point  above 
100°)  is  used  for  "safety  plugs"  in  steam  engines.  When  the  tempera- 
ture approaches  a  point  that  would  be  dangerous,  the  plugs  melt  and 
let  the  steam  escape. 


Cobalt  (sp.  gr.  8.6)  is  a  silver- white  metal.  Its  salts  (acetate,  sul- 
phate, nitrate,  chloride)  are  used  for  sympathetic  ink.  (See  cyclopaedia. ) 

EXP.  122. — Thicken  a  solution  of  cobalt  chloride  with  a  little  pure 
mucilage.  Write  with  a  fine  pen  upon  paper.  The  writing  is  invisible. 
Heat  upon  metallic  support.  The  writing  is  distinctly  blue.  [Dry 
Co  C12  is  distinctly  blue,  but  moist  Co  Cl.2  has  a  pale  pink  color  and  is 
invisible  when  thin  spread.  The  salt  is  deliquescent.]  The  ink  becomes 
invisible  again  when  the  paper  cools. 


Nickel  (sp.  gr.  8.9)  is  a  lustrous  white  metal,  taking  a 
high  polish.  It  is  used  for  plating  iron  to  protect  from 
rusting.  It  is  largely  used  in  alloys. 


Bi,   Co,  Ni,  Mn,  Al,  and  Mg.  105 

EXP.  123. — Repeat  EXP.  122,  using  cobalt  solution,  to  which  nickel 
chloride  has  been  added.  The  writing  is  green.  [Nickel  salts  are  used 
to  make  green  sympathetic  ink.] 


Manganese  (sp.  gr.  8,  fus.  pt.  about  1..8000)  is  a  hard, 
brittle  metal.  It  easily  oxidizes  in  the  air  and  hence  is 
not  found  free.  It  is  best  kept  under  petroleum. 

Manganese  dioxide  (Mn  02,  see  preparation  of  O  and  Cl)  is  its  most 
important  ore.  3Iaiiif anatf  s  (dyad  grouping  Mn  O4)  and  permanga- 
nates (dyad  grouping  Mn2  Ob)  are  largely  used  as  disinfectants. 

EXP.  124. — Place  a  small  piece  of  fresh  meat  in  a  test-tube  of  water 
and  leave  till  putrefaction  begins.  Filter  (through  paper)  and  let  fall 
into  it  a  single  drop  of  dilute  potassium  permanganate  (K2Mn.,08). 
Place  beside  it  a  second  test-tube  of  distilled  water  in  which  the  same 
amount  of  permanganate  has  been  put.  Leave  both  over  night.  The 
permanganate  in  the  first  test-tube  is  decolorized,  having  given  up  a 
part  of  its  0  to  the  decomposed  organic  matter.  In  the  second  the 
color  remains.  [The  presence  of  ferrous  salts,  or  other  easily  oxidizable 
substances,  must  be  avoided.  Water  through  which  the  breath  has 
been  blown  by  means  of  a  glass  tube  answers  for  the  test.] 

Potassium  permanganate  is  a  powerful  oxidizing 
agent  and  is  a  very  delicate  test  for  the  presence  of 
decomposing  organic  matter.  [In  such  tests  be  careful 
not  to  add  too  much  K2  Mn2  O8,  as  of  course  the  excess 
would  not  be  decolorized.] 


Aluminum  (or  aluminium,  sp.  gr.  2.6,  fus.  pt.  700°)  is  a 
bluish-white  metal,  taking  a  bright  polish.  Next  to  sili- 
con and  oxygen  it  is  the  most  abundant  element  in  the 
earth's  crust.  It  does  not  readily  oxidize  in  the  air. 
Delicate,  light  weights,  and,  in  general,  instruments  need- 
ing lightness  and  moderate  strength  are  made  from  alum- 
inum. 


106  CHEMICAL   PRIMER. 


Aluminum  bronze  (Cu  90  per  cent.,  Al  10  per  cent.)  is  a  very  hard 
alloy,  malleable,  has  the  color  of  gold,  and  takes  a  fine  polish. 

Aluminum  oxide  (A1203)  occurs  in  corundum,  ruby,  sapphire,  and 
emery  (impure). 

Common  clay  is  chiefly  aluminum  silicate,  A12  Si2  0T  (there  are 
numerous  silicate  "groupings"),  but  no  cheap  method  of  obtaining  the 
metal  has  yet  been  discovered.  Al  would  be  extensively  used  were  it 
not  for  its  high  price.  (See  GLASS  and  PORCELAIN.) 

Common  alum  is  a  double  sulphate  (A12  K2  4  S  04,  24  H2  0)  contain- 
ing much  water  of  crystallization.  Ammonium  alum  [A12  (H4N)2  4  S  04, 
24  H20]  is  also  somewhat  common.  Alum  is  much  used  as  a  "mor- 
dant" in  dyeing.  (See  DYEING.)  Cryolite  is  Al.,,  F6  +  6  ISia  F. 


Magnesium  (sp.  gr.  1.75,  fus  pt.  about  2,000°,  but  ignit- 
ing point  is  low,  the  flame  of  a  candle  being  sufficient  to 
set  it  on  fire)  is  a  silver- white  metal  not  found  native,  but 
in  combination  is  widely  distributed.  Mg  burns  in  the 
air  with  a  brilliant  light  (Exp.  3),  forming  Mg  O  ("mag- 
nesia"). [In  general,  the  ending  a  means  (1)  the  oxide, 
(2)  the  carbonate,  or  (3)  the  hydrate  of  the  metal.] 

The  light  from  burning  Mg  is  rich  in  chemical  (actinic) 
rays,  and  hence  is  used  for  photographing  in  dark  caves, 
etc.  Arsenicum  is  never  found  with  it,  and  the  metal  is 
used  instead  of  Zn  in  important  tests  for  As.  (See 
Marsh's  test.) 

Mg  C12  is  found  in  sea  water.  Mg  S  04,  7  H2  0  (Epsom  salt)  is  found 
in  many  mineral  waters  and  in  sea  water.  ' '  Magnesia  alba"  is  an  arti- 
ficial mixture  of  Mg  C  03  and  Mg  2  H  0,  principally  the  former.  (See 
magnesite,  hornblende,  meerschaum,  soapstone,  talc,  serpentine,  dolo- 
mite, etc. ,  in  cyclopaedia. ) 


CALCIUM,  STRONTIUM,  AND  BARIUM.     107 


CHAPTER    XXX. 


CALCIUM,  STRONTIUM,  AND    BARIUM. 

Calcium  (sp.  gr.  1.58)  is  a  light-yellow,  ductile  metal. 
It  oxidizes  in  moist  air  and  consequently  is  not  found 
native  (free).  Its  compounds  are  widely  diffused. 

Calcium  oxide  (Ca  O,  quicklime,  a  basic  oxide,  EXP.  5) 
is  prepared  by  heating  the  native  carbonate  (Ca  C  O3)  in 
egg-shaped  "kilns"  till  C  O2  is  all  expelled.  A  kiln  in 
which  the  process  is  continuous  is  shown  in  Fig.  39. 

/ 
Reaction:  Ca  C  O3  =   Ca  O  +  C  O2 

Mixed  with  sand,  hair,  etc.,  according  to  the  purpose 
for  which  it  is  intended,  calcium  oxide  is  used  for  making 
mortar,  cements,  etc. 

The  principal  reactions  are: — 

(1)— Ca  O  +  H2O='Ca2HO 


'water-?lacked 

lime- 


exposed  to  the  air,  this  absorbs  C  Oa  and  hardens. 
(2)— Ca  2  H  O  +  C  O2  =  Ca  C  Os  +  H,O 

"water  slacked  from  "air-slacked  evaporate* 

lime"  aix  lime" 


108 


CHEMICAL   PRIMER. 


Hydraulic  mortars  possess  the 
power  of  hardening  under  water. 
These  are  made  from  quicklime 
that  has  been  prepared  from  cal- 
cium carbonate  containing  a  large 
percentage  of  silicates.  Roman 
cement  is  made  from  calcium  oxide 
containing  from  25  to  35  per  cent, 
of  clay  and  hardens  under  water 
in  a  few  hours.  Chalk  and  clay 
thoroughly  ground  together  with 
water,  dried,  and  carefully  burnt 
in  kilns,  produce  an  impure  quick- 
lime from  which  a  good  hydraulic 
mortar,  called  Portland  cement,  is 
made.  The  hardening  of  these 
mortars,  like  those  above,  depends 
upon  the  formation  of  calcium 
carbonate. 


Fij?.  39.  A— fire.  C-ash-pit.  Calcium  car- 
bonate id  put  in  at  top  of  furnace  and 
calcium  oxide  removed  at  B. 


It 


Ca  0  falls  to  a  powder  when  gradually  air-slacked  by  exposure, 
first  absorbs  wrater  and  then  C  02  as  in  above  reactions. 

Ca  0  is  used  in  the  laboratory  for  drying  gases  (Exps.  45,  56,  and 
illuminating  gas)  and  in  the  "lime  light"  (see  APPENDIX),  the  flame  of 
the  oxy-hydrogen  blowpipe  raising  it  to  the  white  heat  and  causing  it  to 
emit  an  intense  light. 

Calcium  carbonate  (Ca  C  Os)  is  found  as  marble,  lime- 
stone, shells  (chalk  is  formed  by  beds  of  tiny  shells),  sta- 
lactites, etc.,  also  with  Caa  2  P  O4  in  bones.  (See  HARD 
WATER  and  EXP.  51.) 

Calcium  sulphate  (Ca  S  O4,  anhydrite)  and  calcium  sul- 
phate with  water  of  crystallization  (Ca  S  O4,  2  H2O 
gypsum,  plaster,  alabaster)  occur  native.  When  heated 
to  120°,  gypsum  parts  with  its  water  of  crystallization, 
forming  "plaster  of  Paris."  This  plaster  soon  hardens 
("sets")  when  mixed  with  water  and  hence  is  used  as 
cement,  and  for  taking  casts.  (See  WATER  permanently 
hard.) 


CALCIUM,  STRONTIUM,  AND  BARIUM.     109 

Calcium  chloride  (Ca  CL,)  has  so  strong  an  attraction  for  water  that  it 
is  deliquescent.  It  is  used  for  drying  gases  and  is  a  constituent  of 
bleaching  powder  (which  see). 

Calcium  fluoride  (Ca  F2,  fluor  spar)  occurs  native  and  is  used  as  a  flux 
in  the  reduction  of  metals.  The  peculiar  glowing  of  this  mineral  when 
heated  gave  rise  to  the  term  fluorescence.  Hydrofluoric  acid  is  prepared 
from  this  salt  by  the  action  of  sulphuric  acid.  (See  EXP.  86.) 


Barium  (sp.  gr.  4)  and  Strontium  (sp.  gr.  2.5)  resem- 
ble calcium. 


Fig.  40. 


EXP.  125. — Dissolve  a  barium 
salt  in  a  little  dilute  H  Cl.  Make 
a  loop  upon  one  end  of  a  short  plat- 
inum wire  and  fuse  upcn  the  other 
end  a  piece  of  glass  tubing  for  a 
handle.  Introduce  into  the  lower 
and  outer  flame  of  Bunsen's  burner 
(Fig.  40)  by  means  of  this  loop  a 
little  of  Ba  salt  solution.  The 
flame  is  colored  green.  [Ba  C12  dis- 
solved in  water  answers.] 


Barium  salts  (especially  Ba  2  N  O3)  are  used  to  give 
the  color  in  green  fire  (in  pyroteehny)  and  this  color  is  a 
very  good  test  for  soluble  or  volatilizable  salts  of  Ba. 

Barium  sulphate  (Ba  S  04,  heavy  spar)  is  often  used  to  adulterate 
white  lead  (Pb  C  03).  Barium  chloride  (Ba  C12)  is  test  for  soluble  sul- 
phates. (Exp.  94.) 


EXP.  126.— Repeat  EXP.  125,  using  Sr  salt  instead  of  Ba  salt, 
flame  is  colored  red. 


The 


Strontium  salts  are  used  to  give  the  color  in  red  fire, 
and  this  color  is  a  very  good  test  for  soluble  or  volatiliza- 
ble salts  of  Sr. 


no 


CHEMICAL 


IMER. 


CHAPTER 


POTASSIUM,    SODIUM,    AMMONIUM. 

Potassium  (sp.  gr.  .87,  f  us.  pt.  63°)  is  a  light,  bluish- 
white  metal,  soft  enough  (at  15°)  to  be  spread  with  a 
knife. 


EXP.  127.  —  Cut  a  small  slice  of  K  upon 
blotting  paper.  Trim  away  the  edges  and 
throw  the  cleaned  piece  upon  water  in  a 
beaker.  Cover  with  glass  plate  (impurities 
cause  spattering).  The  K  decomposes  the 
water. 


The  reaction  is  so  violent  that  the  liber- 
ated hydrogen  takes  fire,  and  in  burning 
the  heat  volatilizes  a  little  of  the  K,  which 


Fig.  41. 
in  burning  colors  the   flame  purple. 

The  affinity  of  potassium  for  O  is  so  great  that  it  must 
be  kept  under  naptha  (C1UH16  containing  no  O).  EXP.  127 
proves  that  it  cannot  be  found  free  or  native. 

The  compounds  of  K  are  widely  distributed.  They  are  constituents 
of  all  plants  and  of  the  bodies  of  animals.  Potassium  hydrate  (K  H  0 
"caustic  potash")  is  a  white  solid  made  from  K.,  C  O3  by  actioji  of 
Ca  2  H  0  (and  heat). 


K2  C  03     -f     Ca  2  H  0     =    2  K  H  0 


Ca  C  03 


It  is  largely  used  in  -the  manufacture  of  soap.     It  is  one  of  the  strong- 
est alkalies  known.     (See  SOAP  and  ANTIDOTES.  ) 


POTASSIUM,  SODIUM,  AMMONIUM.         Ill 

Potassium  carbonate  (K.z  C  O3  "pearlash")  is  prepared 
by  leaching  wood  ashes,  evaporating  the  "lye"  in  large 
pots  (hence  potash),  and  purifying  by  crystallization.  It 
is  a  deliquescent  salt,  with  a  strong  alkaline  reaction.  It 
(or  Naa  C  O3)  is  largely  used  in  chemical  analysis.  [See 
ANA.  CHARTS,  silver,  lead,  etc.]  It  reacts  with  insoluble 
silicates  by  change  of  partners. 

The  metallic  .  .  the  metallic 

.1.  potassium         potassium 

silicate  +   t  —   r   .v  +     carbonate 

/.       i   1 1  N  carbonate  silicate  ,    i   1 1  \ 

(insoluble)  (soluble) 

"Saleratus"  (H  K  C  03  bicarbonate  of  potash,  acid  salt  with 
alkaline  reaction,  see  ACID-SALTS)  may  be  prepared  by  passing  C  02 
through  strong  solution  of  the  normal  salt  (K2  C  O3). 

H,  0     +     C02     =     H,CO3 
K2C03     +     H2C03     =    2HKC03 

Potassium  nitrate  (K  N  O3  saltpetre,  nitre)  together 
with  Ca  2  N  O3  and  Na  N  O3,  is  formed  by  the  decom- 
position of  refuse  organic  matter.  The  white  incrustation 
often  seen  about  such  matter  is  principally  K  N  O3.  It 
is  a  strong  antiseptic,  and  is  used  with  Na  Cl  (common 
salt)  for  preserving  meat.  It  is  largely  used  in  the  man- 
ufacture of  gunpowder.  When  gunpowder  burns,  the 
reaction  may  be  represented  thus: — 
2  K  N  O3  +  S  +  C3  =  K.2S  +  N2  +  3  C  O2 

solid  solid  solid  gat  at  gat  gat 

oxidizing  combustible     combustible         temperature 

age~t  substance         substance  of  explosion 

Fireworks  are  composed  of  gunpowder  containing  an 
excess  of  C  and  S  with  coloring  matter. 

Potassium  chlorate  (K  Cl  O3)  is  largely  used  for  making  oxygen 
and  as  an  oxidizing  agent.  (Exp.  19,  79,  98,  and  MATCHES.)  It  is 
much  used  in  medicine  to  allay  inflammation  of  the  throat  (as  gargle), 
etc.  K.2Cr2  O7  forms  chrome  yellow  with  lead  salts.  (AxA.  CHARTS.) 
— The  intensely  poisonous  K  C  N  (solution)  dissolves  gold  and  silver 
cyanides  for  electroplating. 


112 


CHEMICAL  PRIMER. 


K  Cl  resembles  Na  Cl.     Potassium  salts  are  largely  used  in  medicine. 

EXP.  128. — Repeat  EXP.  125,  using  potassium  salt  instead  of  barium 
salt.     The  flame  is  colored  purplish. 

This  is  a  fair  test  for  potassium  compounds.      Careful  flame  tests  are 
of  great  value  to  the  experienced  chemist.     (See  SPECTROSCOPE.  ) 


Sodium  (sp.  gr.  .97)  is  a  light,  silver-  white,  soft  metal, 
resembling  potassium.      It  is  used  as  a  reducing  agent  in 

preparing  silicon,  bo- 
ron, magnesium,  and 
aluminum. 

EXP.  129.—  Place  a  small 
clean  piece  of  Na  on  water 
and  quickly  press  below 
mouth  of  inverted  test-tube 
by  means  of  wire  gauze  at- 
tached to  wooden  rod.  The 
water  is  decomposed  and 
the  H,  set  free,  collects  in 


Fig.  42.— Decomposing  Water  by  Sodium. 


test-tube.  (If  Na  is  thrown 
on  hot  water  the  liberated 
H  immediately  takes  fire.) 


Na     +     H20     —     NaHO     +     H 

The  above  experiment  proves  that  sodium  cannot  be 
found  free.  Like  potassium,  it  must  be  kept  under 
naptha. 

EXP.  130.  —  Repeat  EXP.  125,  using  sodium  salt  instead  of  barium 
salt.  The  flame  is  colored  yellow. 

Sodium  chloride  (Na  Cl,  common  salt)  is  the  most 
abundant  of  the  sodium  compounds.  It  is  the  source  from 
which  most  compounds  and  sodium  itself  are  obtained. 
Its  distribution  in  larger  or  smaller  quantities  is  almost 
universal,  traces  which  the  spectroscope  reveals  being 
found  in  the  atmosphere.  It  is  obtained  from  immense 


POTASSIUM,  SODIUM,   AMMONIUM.         113 

deposits  or  beds,  from  saline  springs  and  sea-water  (by 
evaporation).  It  crystallizes  in  cubes.  (See  CRYSTAL- 
LIZATIOX.)  It  is  one  of  our  most  common  antiseptics. 

Sodium  sulphate  (Xa2  S  04  10  H2  0,  Glauber's  salts)  is  remarkably 
efflorescent. 

Sodium  carbonate  (Na2  C  O3  10  H2  O,  sal  soda)  is  ex- 
tensively used  in  the  arts.  It  is  made  by  Leblanc's 
process  :— 

(1)  Common  salt  and  sulphuric  acid  are  heated. 
2NaCl     +     H2S04     =     Na2S  O,     +     2  H  Cl 

The  hydrochloric  acid  is  saved  by  being  absorbed  (see 
EXP.  75,  and  comments)  in  tower  of  coke  wet  with  con- 
stantly falling  water. 

(2)  The  Na2  S  O4  is  heated  with  Ca  C  03  (equal  wt.) 
and  C  (half  its  wt.)  in  a  reverberatory  furnace. 

/ 
(a)— Na2S  O4    +    C2    =    Na2S    +    2  C  O, 

reducing 
agent 

(b)— Na,S    +    CaCO.    -    Na2C  O3    +    Ca  S 

insoluble 


The  Na2C  O3  is  then  washed  out  (lixiviated)  from  the 
"black  ash"  and  purified  by  crystallization  (one  of  the 
most  valuable  known  means  of  purifying  crystallizable 
solids). 

Acid  sodium  caibonate  (H  Xa  C  03,  bicarbonate  of  soda,  "soda" 
of  cook-room,  see  ACID-SALTS)  has  alkaline  reaction,  and  is  prepared  by 
passing  C  0.  into  the  normal  salt  (see  H  K  C  03). 

Sodium  hydrate  (Xa  H  0,  caustic  soda)  is  made  from  sodium  car- 
bonate (just  as  K  H  0  from  K2  C  O:.)  and  is  used  in  the  manufacture  of 
hard  soap. 

Sodium  nitrate  (Xa  X  O3,  Chilian  saltpeter)  is  a  deliquescent  salt. 
8 


114  CHEMICAL   PRIMER, 

Ammonium  (H4N,  a  hypothetical  metal),  as  we  have 
seen,  is  a  compound  radical,  closely  allied  to  K  and  Na. 
Though  it  has  never  been  isolated,  an  alloy  of  ammonium 
and  mercury  (i.  e.,  an  amalgam)  has  been  formed. 

Ammonium  chloride  (H4N  Cl,  sal  ammoniac)  is  used  in  medicine,  in 
dyeing,  in  soldering,  and  in  the  laboratory  as  a  reagent  and  source  of 
ammonia  (H3  N,  see  EXP.  45). 

Ammonium  nitrate  (Exp.  36)  and  ammonium  carbonate  (see  ANTI- 
DOTES) are  important  salts. 

Microcosmic  salt  (H  Na  H4N  P  04  -f  4  H20,  see  DOUBLE  SALTS)  is 

largely  used  in  blowpipe  analysis  as  a  flux. 
ri 


t 

Ammony|Hiydrate  (H4N  H  O  "ammonia  water")  is  a 

very  strong  base  and  is  extensively  used  (dilute)  as  a 
cleansing  agent.     (See  CHEMISTRY  OF  CLEANING.) 


XXXII. 


ORGANIC   CHEMISTRY. 


STARCH,    SUGAR,    ETC. 

Organic  chemistry  treats  of  those  compounds  (composed 
principally  of  C,  H,  N,  and  O,  but  all  containing  C  and 
H)  which  are  formed  chiefly  by  animals  or  plants  in  their 
processes  of  growth  or  partial  decay.  No  line  can  be 
sharply  drawn  between  organic  compounds  and  inorganic. 
Many  compounds  which  formerly  were  supposed  to  be 
produced  only  by  the  "vital  force"  of  the  plant  or  animal, 
have  bean  formed  recently  in  the  laboratory. 


STARCH.  115 


NOTE. — It  is  important  to  remember  that  we  may  make  two  great 
divisions  of  "organic  substances": — 

I.  That  which  is  the  essential  physical  basis  of  life  (bioplasm). 

II.  That  which  is  essential  only  in  a  secondary  sense  and  is  used  by 
the  first  in  accomplishing  its  work  somewhat  as  an  engine  uses  fuel, 
water,  and  the  iron  rails. 

To  this  second  division  belong  crystalline  substances,  fats,  gelatine, 
cellulose,  etc.  Between  the  inorganic  and  this  first  division  of  the 
organic,  a  distinct  line  can  be  drawn.  This  line  bounds  all  possibilities 
of  the  laboratory.  It  is  probably  within  the  province  of  chemistry  to 
produce,  unaided  by  the  "vital  force,"  all  substances  in  this  second 
division.  The  organic  cell  proper,  with  its  subtle  bioplasm,  chemists 
can  never  hope  to  form.  For  example,  the  chemist's  kernel  of  wheat 
will  never  grow.  (See  SPONTANEOUS  GENERATION^  cyclopaedia.) 

As  a  rule,  inorganic  substances  have  few  atoms  in  the  molecule,  while 
molecules  of  organic  substances  frequently  contain  a  very  large  number 
of  atoms.  Often  different  organic  substances  contain  the  same  elements 
in  the  same  proportion.  This  peculiar  relation  is  called  isomerism. 

EXAMPLE. 

Butyric  acid  and  ethyl  acetate,  two  well-known  compounds,  differing 
in  essential  properties,  are  isomeric,  having  the  "empirical  formula" 
(expressing  only  the  proportions  of  the  elements):  C4H802,  but  the 
"rational  formula"  (which  attempts  to  represent  in  some  way  the  arrange- 
ment of  the  atoms  in  the  molecule)  of 

Butyric  acid  =  H  C4H702.     (RET.  TABLE  No.  2,  Continued.) 
Ethyl  acetate  =  C2H5C,H302.     (REF.  TABLE  No.  2.) 

Plants  in  general  prepare  food  for  animals  from  the 
mineral  kingdom,  and  animals,  after  using  it,  return  it  to 
the  mineral  kingdom  again.  The  organic  by  complete 
decay  returns  to  the  inorganic.  The  sun's  light  and  heat 
(Exp.  58)  is  the  motive  power  by  which  the  plant  is  ena- 
bled to  build  up  the  organic  out  of  the  inorganic. 

Starch  (C6HleO5)  is  a  substance  found  in  all  cereals, 
in  many  roots,  stems,  and  fruits.  It  is  composed  of  grains, 
which  the  microscope  reveals  differing  in  size  and  shape 
in  different  plants.  These  grains  swell  up  and  burst  on 


116  CHEMICAL  PRIMER. 

heating  with  water.  Its  use  for  food,  in  the  laundry,  etc., 
is  well  known.  Arrow-root  and  tapioca  are  varieties  of 
starch  from  roots  of  tropical  plants.  Sago  is  starch  from 
the  pith  of  the  sago-palm. 

The  test  of  starch  is  iodine,  with  which  it  forms  a  blue  compound. 
(Exp.  84.) 

EXP.  131. — Scrape  some  potato  into  cold  water  and  squeeze  through 
a  linen  cloth  several  times.  The  insoluble  starch  remains  suspended  in 
the  filtrate,  while  the  woody  fiber  (cellulose)  remains  upon  the  filter. 
After  subsidence,  pour  off  the  water,  and  dry.  This  illustrates  the 
method  of  obtaining  starch  from  the  potato. 

When  starch  is  heated  to  about  205°,  it  changes  into  an  isomeric  com- 
pound, dextrin,  much  used  instead  of  gum  arabic  in  making  adhesive 
stamps.  Dextrin  is  also  formed  if  starch  is  boiled  with  water  slightly 
acidulated  with  sulphuric  acid.  If  the  boiling  is  continued  longer,  the 
dextrin  is  converted  into  starch-sugar  (C6H1206).  Dextrin  gives  no  blue 
color  with  iodine. 

Gum  arabic  (C^H^On)  exudes  from  a  species  of  acacia.  Pectose 
is  a  gummy  substance  found  in  many  fruits  and  vegetables. 

Cellulose  (C18H30015);  or  woody  fiber,  is  the  frame-work  of  the  cells 
of  plants,  and  is  found  in  every  part,  even  in  the  pulpy  fruits.  Linen, 
made  from  the  inner  bark  of  flax,  and  cotton — the  hollow  white  hairs 
around  the  seed  of  the  cotton  plant— are  nearly  pure  cellulose.  (See 
cyclopaedia.)  If  paper  is  dipped  in  dilute  sulphuric  acid  (2  vols.  H2S  04, 
1  vol.  H20)  for  a  few  moments,  tough  parchment  paper  results. 

Gun-cotton  is  cellulose,  in  which  part  of  the  H  has  been  replaced  by 
the  negative  radical  N  0.2,  by  dipping  in  a  mixture  of  H  N  03  and 
H2S  04.  It  is  very  explosive. 

Gun-cotton,  dissolved  in  ether  (ethyl  oxide)  and  alcohol  (ethyl 
hydrate)  forms  collodion,  much  used  by  photographers. 

Celluloid  is  made  chiefly  from  gun-cotton  and  camphor,  by  submitting 
to  great  pressure.  It  can  be  colored  in  imitation  of  coral,  made  into  col- 
lars and  cuffs,  and  substituted,  in  general,  for  ivory.  Its  manufacture  is 
comparatively  a  new  industry. 


,  sucrose  (C12H.22On),  may  be  obtained  from 
xthe  sugar-cane,  beet-root,  maple,  and   certain   kinds  of 


STARCH.  117 


palm.  In  making  it  from  the  sugar-cane  (1)  the  canes 
are  crushed,  (2)  lime  (Ca  O)  is  added  to  the  juice  to  neu- 
tralize any  acid  formed  by  fermentation,  (3)  the  liquid  is 
evaporated  to  thick  syrup,  (4)  set  aside  to  cool,  (5)  the 
sugar  crystallizes,  forming  brown  sugar,  (6)  it  is  put  into 
perforated  casks  to  drain.  The  drainings  ("mother  liq- 
uor") are  molasses. 

In  the  process  of  refining,  brown  sugar  is  (1)  dissolved, 
(2)  pumped  to  upper  story  of  the  high  building,  (3) 
filtered  through  twilled  cotton  bags,  kept  in  bath  of  steam, 
(4)filtered  through  animal  charcoal  (Exp.  48),  (5)  evapo- 
rated in  ''vacuum  pans"  (kettles  from  which  air  and  steam 
are  partially  removed  by  pump,  so  that  the  syrup  boils  at 
a  lower  temperature  and  does  not  burn),  and  (6)  set  aside 
to  crystallize.  If  in  moulds,  loaf -sugar  results ;  if  in  cen- 
trifugal machines,  granulated.  The  drainings  are  syrup 
or  sugar-house  molasses. 

Caramel  is  sugar  carefully  "burnt"  so  that  it  loses  part,  but  not  all, 
of  its  elements  of  water.  It  is  used  for  coloring  liquors,  flavoring  confec- 
tioneries, etc. 

Cane-sugar  is  not  found  in  animal  tissues  or  secretions,  but  is 
changed  in  the  alimentary  canal  before  absorption  into  grape  sugar. 
[Medical  students  should  master  all  the  tests  for  grape  sugar  in  the  APPEN- 
DIX.] 

Grape-sugar  (C6H1UO6).  glucose  (dextrose,  starch-sugar,fruit-sugar), 
is  found  in  honey,  figs,  grapes,  and  many  kinds  of  fruit.  It  has  much 
less  sweetening  power  than  cane-sugar. 

EXP.  132. — To  a  solution  of  grape-sugar  (made  by  boiling  a  few 
raisins  in  water  and  filtering)  add  three  drops  of  copper  sulphate  (5  per 
cent,  solution  and  slightly  acidulated  with  acetic  acid),  then  add  strong 
solution  of  K  H  O  (potash  or  Isa  H  O,  soda)  till  the  light  blue  color  of 
liquid  becomes  darker.  Raise  to  the  boiling  point,  but  do  not  boil 
beyond  a  few  seconds.  A  yellowish-red  precipitate  of  cuprow<s  oxide 
(Cu2  0)  falls.  This  is  a  delicate  test  for  sugar  in  animal  secretions 
(grape-sugar,  or  milk-sugar  isomeric  with  cane).  (See  ADD.  Exp.) 


118  CHEMICAL   PRIMER. 


EXP.  133. — Divide  a  solution  of  cane-sugar  into  two  parts;  apply  test 
as  in  EXP.  132,  no  cuprous  oxide  falls.  Slightly  acidulate  the  second 
portion  with  H2S  04,  and  boil  to  syrup.  The  cane-sugar  changes  to 
grape-sugar.  Dilute  and  apply  test.  Yellowish-red  Cu2O  falls. — Boil 
for  some  time  a  minute,  quantity  of  starch  in  dilute  (2  percent. )  sulphuric 
acid.  The  starch  changes  to  grape-sugar.  Divide  into  two  portions 
and  test  the  first  by  iodine;  no  starch  is  found.  Test  the  second;  grape- 
sugar  is  found.  Boil  cellulose  (woody  fiber  free  from  pitch)  in  dilute 
H2S  04  and  grape-sugar  is  found  in  the  solution. 

The  insoluble  starch  laid  up  in  the  seeds  of  plants  is 
converted  into  (soluble)  sugar  by  the  action  of  a  nitroge- 
nous substance,  called  diastase,  in  the  presence  of  warmth 
and  moisture.  The  sugar  is  then  absorbed  by  the  grow- 
ing plantlet,  and  is  built  into  its  structure  as  woody  fiber, 
etc. 


Fermentation  is  a  species  of  decay.  A  necessary 
condition  is  the  presence  of  some  nitrogenous  ("albumi- 
nous") substance,  called  a  ferment,  and  the  growth  therein 
of  a  fungus  plant  called  yeast.  This  plant  is  of  a  low 
order,  and  spreads  by  the  rapid  multiplication  of  cells 
throughout  the  whole  fermenting  substance,  if  it  has  the 
needed  warmth  (about  30°)  and  moisture.  In  the  fer- 
mentation of  substances  containing  grape-sugar  (or  cane- 
sugar,  which  changes  to  grape-sugar),  there  are  two 
stages:— 

1.  The  Alcoholic  Fermentation,  in  which  the  sugar 
breaks  up  into  alcohol  and  carbon  dioxide. 

C6H12O6    =-2C,H6HO    +    2  CO, 


alcohol  ca  boil 

dioxide 


2.  The  Acetic  Fermentation,  in  which,  by  exposure 
to  the  air,  the  alcohol  is  oxidized,  forming  acetic  acid  and 
water. 

C2H5HO    +    O,    =    HC2H302    +    H20 


ethyl  hydrate  from  the  acetate  acid 

air 


ALCOHOL,  ETC.  119 

NOTE. —  The  two  reactions  above  explain  thoroughly  the  principal 
results  of  fermentation.  It  is  evident  that  the  second  stage  can  be  pre- 
vented, if  the  air  (oxygen)  be  excluded  from  the  fermenting  material. 
The  first  stage  cannot  be  prevented  "by  bottling,"  provided  there  is  in 
the  substance  sufficient  nitrogenous  material  (ferment),  and  provided 
the  yeast  spores  have  not  been  killed  by  boiling  or  by  an  antiseptic.  The 
second  stage  follows  the  first  very  rapidly,  if  the  temperature  is  raised 
(to  about  38°,  or  100°  F).  This  explains  the  rapid  "souring"  of  sub- 
stances in  hot  weather.  The  fermentation  ("working")  in  preserves 
may  be  checked  by  boiling  and  then  excluding  the  air,  thus  shutting  out 
the  yeast  spores. 

Beer,  ale,  etc.,  are  made  from  malt  (grain  that  has  germinated  suf- 
ficiently to  change  nearly  all  the  starch  to  sugar,  and  in  which  the  fer- 
mentation has  been  checked  by  drying).  The  malt  is  crushed,  water 
added,  and  heat  applied  to  turn  starch  to  sugar.  It  is  then  cooled,  hops 
and  yeast  are  added,  when  the  alcoholic  fermentation  at  once  commences. 

Wine  is  made  by  the  fermentation  of  grape  juice.  If  all  the  sugar  is 
converted  into  alcohol  and  C  Oa,  dry  wine  results.  If  the  fermentation 
ceases  (from  an  excess  of  sugar  over  the  ferment)  when  only  part  of  the 
sugar  is  changed,  sweet  wine  results.  Efferyescinff  wine  is  sealed 
in  strong  bottles  while  the  alcoholic  fermentation  is  going  on.  In  sour 
wine  the  acetic  stage  has  somewhat  progressed. 

When  any  fermented  liquor  is  distilled,  the  alcohol  (having  a  lower 
boiling  point  than  water)  first  passes  over  through  the  condenser 
(Fig.  19),  together  with  certain  flavoring  substances  and  a  certain  part  of 
the  water.  Brandy  is  made  by  distillation  from  wine;  rum  from  fer- 
mented cine-juice;  whisky  from  fermented  corn,  rye,  or  potatoes;  gin 
from  fermented  barley  and  rye,  and  afterwards  distilled  with  juniper- 
berries  (flavoring). 

Alcohol  (C2  H5  H  O  ethyl  hydrate)  is  the  intoxicating 
principle,  of  all  varieties  of  (unadulterated)  "liquors."  It 
is  a  colorless,  volatile,  inflammable,  poisonous  liquid.  Its 
flame,  as  we  have  noticed,  is  hot  and  smokeless.  It  is  a 
valuable  solvent.  Many  substances,  as  resins,  etc.,  insol- 
uble in  water,  are  soluble  in  alcohol.  A  solution  of  a  sub- 
stance (medicinal)  in  alcohol  is  a  tincture.  (See  VOLA- 
TILE OILS.)  Strong  alcohol  contain. >  about  10  per  cent. 


120  CHEMICAL  PRIMER. 

water,  all  of  which  cannot  be  removed  by  distillation.  It 
may  be  removed  by  Ca  O,  or  some  other  substance  which 
has  a  great  affinity  for  water,  when  anhydrous,  or  abso- 
lute alcohol,  remains.  Anhydrous  (white)  Cu  S  O< 
(Exp.  34)  is  test  for  absolute  alcohol.  If  water  is  present, 
the  sulphate  turns  blue.  Common  alcohol  belongs  to 
marsh  gas  series.  Strong  alcohol  is  an  antiseptic. 

Common  Ether  (C2H5)  A  ethyl  oxide,  is  made  by  dis- 
tilling alcohol  in  presence  of  sulphuric  acid.  It  is  a  very 
volatile,  inflammable  liquid.  It  produces  great  "cold"  by 
its  evaporation.  If  blown  in  a  fine  spray  (from  atomizer) 
upon  some  part  of  the  body,  the  rapid  cooling  produces 
local  anaesthesia  by  "freezing"  (chilling)  the  spot.  It  is 
inhaled  as  an  anaesthetic,  and  is  a  valuable  solvent. 

There  is  a  large  number  of  alcohols  (hydrates  of  positive  radicals)  and 
corresponding  ethers  (oxides)  arranged  in  series.  Methyl  alcohol 
(C  H3  H  0,  wood  spirit)  is  formed  by  the  destructive  distillation  of 
wood,  and  resembles  ethyl  or  common  alcohol  in  many  particulars. 
Amyl  alcohol  (C5HUHO,  fusel  oil)  has  a  very  fetid  odor,  and  is 
much  more  poisonous  than  C2H5  H  0.  It  is  formed  in  small  quantities 
in  the  fermentation  of  potatoes  and  grain.  Its  boiling  point  is  137°, 
while  that  of  ethyl  alcohol  is  only  78°.  The  common  alcohol  is  sepa- 
rated from  it  "by  fractional  distillation,  a  valuable  method  of  separating 
liquids  whose  boiling  points  differ  materially. 

The  salts  of  the  positive  groupings  of  the  ethers,  or 
alcohols,  are  often  termed  "compound  ethers"  (Ex.: 
ethyl  ^rate,  C2H5N  O3,  etc.).  Many  of  these  "compound 
ethers"  are  sold  as  "essences,"  and  they  very  closely  imi- 
tate the  Arue  essences.  Ethyl  butyrate  (C2H5CJI7O2)  is 
sold  as  "essence  of  pine-apple." 

Chloroform  (C  H  C13)  is  made  by  distilling  alcohol 
with  "chloride  of  lime."  It  is  a  colorless,  volatile  liquid, 
used  as  an  anaesthetic  and  as  a  solvent. 


ALCOHOL,  ETC.  121 


Chloral  (C2H  C130),  a  colorless,  oily  liquid,  is  made  by  passing  dry 
chlorine  into  alcohol.  It  combines  with  water  of  crystallization,  form- 
ing a  white  crystalline  substance,  the  so-called  chloral  hydrate 
(C,  H  C13  0  H2  0).  Chloral,  when  taken,  reacts  with  the  alkali  of  the 
blood,  producing  chloroform  and  inducing  sleep.  It  is  much  used  in 
medicine. 

Acetic  acid  (H  C2H302,  the  acid  of  vinegar),  as  we  have  seen,  is  pro- 
duced by  the  fermentation,  under  the  proper  conditions,  of  substances 
containing  sugar.  It  is  produced  in  the  second  stage  by  the  oxidation  of 
alcohol.  Strong  acetic  acid  crystallizes  at  17°  and  is  called  glacial. 
The  "mother"  of  vinegar  is  a  fungus  plant;  it  assists  the  fermentation 
by  absorbing  O  from  the  air  and  giving  it  up  to  oxidize  the  alcohol. 
When  the  alcohol  is  all  gone,  however,  it  works  mischief.  The  vinegar 
itself  is  oxidized  and  destroyed  (destructive  fermentation).  Sulphuric 
acid  and  pungent  spices  are  often  added  to  vinegar  to  increase  its 
strength.  One  gallon  of  sulphuric  acid  in  a  thousand  gallons  of  vinegar 
is  used  to  prevent  the  destructive  fermentation.  A  large  quantity  of 
H2  S  04,  however — such  as  is  added  by  some  unscrupulous  dealers  to 
make  weak  vinegar  strong — is  exceedingly  injurious. 

Carbolic  acid  (C6H5H  O,  phenyl  hydrate),  better  classed 
with  the  alcohols  (of  phenyl  series),  is  obtained  from  coal- 
tar.  It  is  a  very  fwi^onous  liquid  (it  may  be  obtained 
crystallized)  and  is  a  powerful  antiseptic  and  disinfect- 
ant. Carbolic  acid  is  sometimes  confounded  with  creosote 
(C8H18O2),  the  antiseptic  principle  of  smoke  (by  which 
"bacon,"  etc.,  is  "cured");  indeed,  impure  carbolic  acid  is 
commonly  called  creosote.  (See  ANTIDOTES.) 

Benzol  (C6H5H,  phenyl  hydride — see  ILLUMINATING  GAS)  is  a  very 
volatile,  inflammable  liquid,  is  a  valuable  solvent,  and  is  used  to  remove 
grease  spots  from  silk  and  woolen  articles.  From  it,  by  the  action  of 
nitric  acid,  nitrobenzol  (C6H5N  O.J,  an  oily  liquid  is  prepared.  By  the 
action  of  reducing  agents  upon  nitrobenzol  the  celebrated  aniline 
(C6H7N),  the  source  of  the  * 'coal-tar"  dyes,  is  prepared.  (See  DYEING.) 

(For  tar,  coal-tar,  naphtha,  benzine,  kerosene  oil,  dead-oil,  petroleum, 
bitumen,  etc. ,  see  cyclopaedia. ) 


122  CHEMICAL   PRIMER. 

There  are  three  great  classes  of  (organic)  foods: — 

1.  Starch,  sugar,  and  allied  bodies. 

2.  Oleaginous  substances.     (See  CHAP,  xxxiv.) 

3.  Albuminous  substances  ("nutritious  matter,"  nitrog- 
enous matter). 

Albumen  (formula  very  complex,  composed  of  C,  H,  N,  S,  and  0)  is 
found  nearly  pure  in  white  of  eggs.  Albuminous  matter  possesses  the 
power  of  (1)  becoming  a  ferment,  (2)  of  coagulation,  and  (3)  of  putrefac- 
tion. Casein  is  found  in  milk,  and  is  coagulated  by  rennet  (acid); 
gluten,  in  flour,  meal,  etc.;  iibrin,  in  blood,  and  another  variety  of 
fibrin  in  muscular  tissue.  (Medical  students  see  ADD.  EXP.  for  tests.) 

EXP.  134. — Soak  a  small,  clean  bone  over  night  in  H  Cl  (30  per  cent.). 
The  mineral  matters  are  dissolved,  and  the  soft  animal  matter  left. 
Wash  thoroughly  in  water  and  leave  in  water  over  night  again.  Boil 
the  animal  matter  for  some  time  in  a  small  quantity  of  water  and  set 
aside  to  cool.  A  gelatinous  substance  remains. 

Gelatin  (formula  complex;  a  nitrogenous  substance  not  belonging  to 
albuminous  matter  proper]  is  formed  by  the  action  of  hot  water  upon 
animal  membranes,  tendons,  and  bones.  Crlue  is  very  impure  gelatin. 
Isinglass  is  a  very  pure  gelatin  from  the  air-bladders  of  fish.  (The 
mineral,  mica,  used  in  the  doors  and  sides  of  parlor  stoves,  is  often  im- 
properly called  isinglass. } 

' 

"CHEMISTRY    OF    COOKING. 

Flour  consists  of  gluten,  starch,  and  a  little  dextrin 
and  sugar.  The  oily  and  mineral  substances  are  con- 
tained chiefly  in  the  bran  of  grain,  hence  "coarse  food," 
as  corn  meal,  graham  flour,  oatmeal,  cracked  wheat,  etc., 
are  very  necessary  for  the  proper  development  of  bone 
and  sinew. 

In  bread-making  the  flour,  mixed  with  milk  (or  water) 
containing  yeast,  is  set  in  a  warm  place,  and  immediately 
the  alcoholic  fermentation  begins.  The  carbon  dioxide 
set  free  is  held  by  the  gluten,  causing  the  dough  "to  rise." 
This  is  kneaded,  to  distribute  evenly  the  fermentation  and 
to  break  up  the  large  bubbles  of  C  Or 


CHEMISTR  Y  OF  COOKING.  1 23 

In  baking,  the  C  O2  and  alcohol  escape.  If  the  oven 
is  too  hot,  a  crust  forms  too  quickly,  prevents  the  escape 
of  the  C  O2,  and  large  cavities  are  formed.  If  the  fire 
is  not  hot  enough,  the  C  O2  escapes  before  the  cells  are 
sufficiently  hardened,  and  the  bread  falls.  Sour  bread  is 
formed  when,  before  (or  while)  baking,  the  second  stage 
(acetic)  of  fermentation  is  reached.  The  acetic  stage 
follows  the  alcoholic  very  rapidly  if  the  temperature  of 
fermentation  is  high.  (See  NOTES  under  FERMENTATION.) 
A  very  slow  fire  in  baking  may  produce  the  same  result. 
Saleratus  (H  K  C  O3,  or  soda  H  Na  C  O3,  acid  salts,  but 
these  have  alkaline  reaction),  is  added  to  neutralize  any 
acid  that  may  be  formed  by  this  second  fermentation. 

In  raising  biscuit,  "soda"  and  "cream  of  tartar" 
(H  K  C4H4O6)  are  used  to  furnish  the  C  O2,  while  the  salt 
that  remains  is  a  harmless  one. 

Common  baking  powder  is  merely  "cream  of  tartar" 
and  "soda,"  but  it  is  often  adulterated  with  alum,  to  make 
inferior  flour  look  white.  Bread  containing  alum  is 
highly  injurious,  producing  chronic  constipation.  (See 
test,  ADD.  EXP.) 

"Yeast  cakes"  are  made  by  exposing  'moistened  corn 
meal  (or  other  similar  substance)  containing  a  ferment,  to 
moderate  temperature  till  the  gluten  is  in  the  midst  of  the 
alcohol  fermentation.  The  fermentation  is  then  checked 
by  drying.  The  yeast  plant  (fungus)  throughout  the 
cake  may  be  likened  to  so  much  dry  seed,  which  needs 
only  to  be  sown  in  the  right  soil  (in  the  dough). 

The  chemical  changes  in  the  body  (Physiological 
Chemistry)  are  too  difficult  for  insertion  in  a  primary 
work. 


124  CHEMICAL  PRIMER. 


CHAPTER    XXXIII. 


VEGETABLE  ACIDS  AND  BASES  (ALKALOIDS). 

Compounds  of  oxalic  acid  (H2C2O4  2  H2O),  especially 
K2C2O4,  and  Ca  C2O4  are  found  in  rhubarb,  sorrel,  etc. 
(also  a  very  little  of  the  free  acid).  The  acid  is  a  power- 
ful poison.  It  is  sold  as  "salts  of  lemon"  (a  dangerous 
name),  to  remove  ink  stains.  It  used  to  be  very  expen- 
sive, but  it  is  now  made  on  a  large  scale  by  heating  saw- 
dust and  caustic  potash  (K  H  O).  (See  ANTIDOTES  and 
CHEMISTRY  OF  CLEANING.) 

Salts  of  tartaric  acid  (H2C4H4O6),  also  minute  quanti- 
ties of  the  free  acid,  exist  in  many  fruits,  and  especially 
in  the  grape  (as  acid  potassium  tartrate,  H  K  C4H4O6,  see 
ACID-SALTS).  It  settles  during  fermentation,  forming 
a  crust  ("argol,"  "bitartrate  of  potash")  which,  when 
purified,  is  cream  of  tartar  (H  K  C4  H4  O6).  Tartar 
emetic  is  a  double  salt:  potassium  antimonyl  tartrate 
(K  SFO  C  JlTOe).  Rochelle  salt  is  K  Na  C4  H4  O6. 

Citric  acid  (H3C6H5O7H2O)  is  the  acid  of  the  lemon, 
lime,  etc.  Its  salts  are  also  present. 

Malic  acid  (H3C4H3O5)  occurs  (together  with  potassium 
malate)  in  most  unripe  fruits,  especially  unripe  apples. 

Tannic  acid  (H3C27H19017 — tribasic  ?),   or  tannin,  is 

found  in  the  leaf  and  bark  of  most  trees  and  of  many 
shrubs  (oak  especially,  in  nut  galls,  hemlock,  etc.),  together 
with  a  little  gallic  acid^(H3C7H3O5,  H2O). 


THE  OR  Y  OF  TYPES.  1 25 

EXP.  135. — To  a  solution  of  tannic  acid  add  a  solution  of  gelatin  (from 
EXP.  134);  a  yellowish-white  precipitate  of  gelatin  tannate  falls. 

In  the  process  of  tanning,  the  tannic  acid  unites  with 
the  gelatin  of  the  hide,  forming  a  tough  compound 
(leather). 

EXP.  136. — To  a  solution  of  tannic  acid  add  copperas  solution.  Ink 
is  formed,  becoming  darker  by  exposure  to  the  air.  (Qua  salts  of  Fe 
have  a  tendency  to  oxidize  and  form  peculiar  and,  as  a  rule,  less  soluble 
"oxy-salts"). 

3  Fe  S  04    +    2  H3C27H19017     =    Fe32  C,7H19017     -f     3  H,S  O4 

copperas  tannic  acid  INK  corrodes  pens 

Leather  is  blackened  by  washing  one  side  with  solution 
of  iron  sulphate,  thus  covering  it  with  ink.  Carbolic  acid 
or  corrosive  sublimate  (Hg  C12),  antiseptics,  are  used  to 
keep  ink  from  moulding. 


The  alkaloids  are  organic  bases  (see  comments,  EXPS. 
4  and  5),  and  they  form  salts  on  the  ammonia  type. 
Many  of  them  have  a  bitter  taste,  are  powerful  poisons, 
and  valuable  medicines.  (See  ANTIDOTES.)  The  liquid 
alkaloids  (few)  contain  C,  H,  and  N,  while  the  solid 
(nearly  all)  contain  C,  H,  N,  and  O.  Their  salts  occur 
in  the  plants  from  which  they  are  obtained. 


THEORY    OF    TYPES. 

The  theory  of  types  has  done  much  to  advance  the  science  of  chemis- 
try. The  pupil,  however,  must  distinguish  between  theory  and  fact. 
The  formation  of  compounds  on  the  water-type  is  strictly  represented 
thus:— 


O     =     water 


NO 


H 


O    =    nitric  acid 


in  which  the  negative  radical,  nitryl  (N  02),  replaces  an  atom  of  H  in 
the  molecule  of  water.     So:  — 

TT        I  O     f\ 

'  =  2 


O2    =    two  molecules  of  water,  2    Ov     =     sulphuric  acid 


126 


CHEMICAL   PRIMER. 


in  which  two  atoms  of  H  in  the  water  have  been  replaced  by  the  negative 
radical  sulphury  1,  S  02.  The  reaction  in  EXP.  16,  written  strictly  to 
represent  the  water- type,  becomes: — 


Na 
H 


0 


C2H30 
H 


0      = 


3 

N 


0 


0 


It  is  easily  seen  how  the  negative  radical,  usually  considered  by 
chemists  as  the  replaceable  and  replacing  quantity  in  reactions,  is 
obtained  from  the  negative  ''grouping,"  viz.:  by  subtracting  one  atom 
of  0  from  monad  groupings,  two  from  dyad  groupings,  etc.  Negative 
radicals  usually  take  the  termination,  yl 

Again,  binary  acids  and  salts  cannot  in  any  strict  sense  be  referred  to 
the  water-type  as  in  this  book,  but  must  be  referred  to  the  hydrochloric 
acid  type. 

The  formation  of  compounds  on  the  ammonia  type  is  shown  in  the 
following  formulas,  the  connecting  element  being  the  triad,  nitrogen. 
The  examples  given  are  artificial  compounds  (alkaloids): — 


C6H5 

N     —     ammonia        H 
H 


C2H5 
C2H5 


N    diethyl-amine    C.2 


phenyl- 
amine 
(aniline) 

CA 

H 

N  ethyl-amine 

CTT 
a-tts 

C,H5    N 

CTT 
9X15 

triethyl-amine 

If  the  H  of  ammonia  (one  or  more  atoms)  is  replaced  by  a  positive 
radical,  an  amine  results;  if  by  a  negative  radical,  an  amide;  if  a  posi- 
tive and  a  negative  both  take  part  in  the  replacement,  an  alkalamide — 
all  giving  rise  to  very  hard  names. 


The  ammonia  type  should  be  considered  only  in  this 
respect  by  beginners.  Ammonia  forms  salts  with  the 
acids,  without  replacing  the  hydrogen  of  the  acid.  The 
alkaloids  do  the  same  thing. 

EXAMPLES. 

H3  N  +  H  Cl  =  H4N  Cl  or  H3  N  H  Cl  =  chloride  of  ammonia 
CeH7N    +    HC1    =    C6H7NHC1    —    chloride  of  aniline 

(  chloride  or 
C17H19N  03  -f  H  Cl  =  C17Hi9N  O3  H  Cl,  3  H20  =    I  hydrochlorate 


water  of 
crystallization 


of  morphine 


ALKALOIDS.  127 

Morphia  (C17H19N  03,  H2O),  or  morphine,  is  the  priru 
cipal  alkaloid  in  opium,  the  dried  j  uice  of  the  poppy.  In 
small  doses  it  acts  as  a  sedative;  in  large  doses,  as  a  nar- 
cotic poison.  It  is  combined  with  meconic  acid  in  the 
plant  as  meconate  of  morphia.  A  salt  of  morphia  (sul- 
phate or  chloride,  usually)  is  sold  at  the  drug  stores  as 
"morphia,"  and  the  same  is  true  of  many  other  alkaloids. 
Laudanum  is  tincture  of  opium ;  paregoric,  a  camphora- 
ted tincture,  flavored  with  aromatics.  Many  patent  con- 
coctions for  "soothing"  children  contain  opium,  and  are 
very  pernicious. 

Quinia,  or  quinine  (C.29H24N2Oa  3  H2O),  is  obtained  from 
the  bark  of  the  cinchona,  a  tree  found  native  in  Peru.  It 
is  largely  used  in  medicine,  especially  in  feverSo  It  has  a 
bitter  taste.  In  large  or  long  continued  doses  it  is  apt  to 
impair  the  hearing. 

Aconitia,  or  aconite  (C54H4WN  O2),  is  obtained  from 
aconite  leaves  and  root.  It  is  used  in  fevers  to  cause  per- 
spiration (sudorific).  It  is  one  of  the  most  violent  poisons 
known. 

Strychnia,  or  strychnine  (C21H22N2O2),  is  the  alkaloid 
in  nux  vomica  (seeds)  and  the  St.  Ignatius  bean.  It  is 
also  one  of  the  most  poisonous  of  the  alkaloids.  It  is 
largely  used  in  medicine  as  a  nervous  tonic.  It  is  in- 
tensely bitter. 

Atropia  (C17H2SN  O3)  exists  in  belladonna,  or  Deadly 
Nightshade,  as  malate  of  atropia. 

Nicotia,  or  nicotine  (C19H14N2),  is  the  volatile  liquid 
alkaloid  of  the  tobacco  plant.  It  is  intensely  poisonous, 
but  unfortunately,  being  so  volatile,  its  smoke  does  not 
kill.  The  human  system  at  length  becomes  tolerant  of 
the  presence  of  the  poison,  even  in  the  stomach, 


128  CHEMICAL  PRIMER. 

As  a  rule,  it  stupefies  and  clouds  the  intellect,  especially 
of  persons  not  full  grown.  Those  boys  who  are  great 
smokers  rarely  take  a  high  standing  in  their  classes. 

The  alkaloids  are  very  numerous,  as  are  also  the  vegetable  acids. 
For  fuller  account  of  each  see  cyclopaedia,  also  see  ANTIDOTES.  [Med- 
ical students  should  master  the  tests  in  APPENDIX.] 


XIV. 


OILS,  FATS,  RESINS,  ETC 

There  are  two  great  classes  of  oils:  Fixed  and  Volatile 
(or  Essential).  Fixed  oils  cannot  be  distilled  ^without 
decomposition  into  various  hydrocarbons.  Volatile  oils 
can  be  readily  distilled. 

Fixed  oils  are  salts  (using  the  term  in  a  wide  sense). 
Hard  fat  is  principally  glyceryl  stearate  ("stearin"),  soft 
fat,  glyceryl  palmitate  ("palmitin"),  and  liquid  fat,  glyc- 
eryl oleate  ("olein").  Fixed  oils,  when  boiled  with  an 
alkali  (K,  Na,  etc.,  hydrate),  react  with  the  alkali  to  form 
a  "soap,"  and  "glycerinee"  (TABLE  No.  2.) 

EXP.  137° — Mix  a  strong  solution  of  "caustic  soda"  (Na  H  0)  with 
olive  oil  and  boil  for  about  twenty  minutes. 
3NaHO    +    C3H53C18H3a02    =    3  Na  C18H8SOa    +    C3H5  3  H  O 

sodium  glyceryl  oleate  sodium  oleate  glyceryl  hydrate 

hydrate  (olive  oil)  (hard  soap,  because  it  Is  (glycerine) 

not  a  deliquescent  salt) 

Add  a  little  of  solution  of  common  salt.  (Soap  does  not  dissolve  in 
salt-water., )  Set  aside  to  cool,  the  soap  and  glycerine  separate. 

Olive  oil  contains  some  glyceryl  palmitate,  so  that  the 
soap  is  partly  sodium  palmitate.  If  tallow  be  taken  in 
place  of  olive  oil,  the  soap  is  principally  sodium  stearate. 


GILS,  FATS,  RESINS,  ETC.  129 

Inspection  of  the  reaction  revea's  the  whole  story  of  soap- 
making.      If  "caustic  potash"  is  taken,  the  reaction  be- 
comes 
3  K  H  O  +  C3H5  3  C18H3302  =  3  K  C18H33O2  +  C3H6  3  H  O 

caustic  potash  glyceryl  oleate  toft  boap,  because  glycerin* 

potassium  oleate  is 
a  deliyitctcent  salt 

Potassium  forms  a  soft  soap  and  sodium  a  hard  soap. 
Ca  forms  an  insoluble  "lime  soap."  Mg  also  forms  an 
insoluble  soap.  Insoluble  soaps  are  sometimes  used  in 
medicine  and  in  the  arts.  Solutions  of  soluble  soaps  (K 
and  Na)  are  good  solvents  of  the  cuticle  and  of  many 
forms  of  "dirt,"  and  hence  are  valuable  cleansing  agents. 
They  must  be  used,  however,  with  soft  water,  or  there 
is  a  great  waste  of  the  soap.  If  soft  soap,  for  instance, 
is  put  into  hard  water  (e.g.,  containing  Ca  S  O4,  or  other 
soluble  sulphate),  the  soap  is  destroyed,  and  an  insoluble 
"lime  soap"  formed  by  the  following  reaction: — 

CaSO4   +   2KC18H33O2    =    K,S  04   +    Ca  2  C18H33O2 

soft  soap  insoluble  lime  soap 

A  similar  reaction  takes  place  if  the  water  is  only  of 
temporary  hardness.  (See  EXP.  33.)  Water  of  tempo- 
rary hardness,  as  we  have  seen,  is  softened  l>y  boiling. 
Water  of  permanent  hardness  may  be  softened  (for  wash- 
ing purposes)  by  adding  borax  (Na2B4O7),  or  washing  soda 
(Na.2C  O3,  10  H,O).  If  the  last, 

Ca  S  O,    +    Na2C  O3    =     Na,  S  O4    +    Ca  C  O, 

cause  of  (remaining  in  sulu  ion  precipitate 

hardness  but  not  affecting 

the  soap) 

In  making  "lye"  from  wood  ashes,  the  ashes  are 
leached  in  a  large  tub  containing  "lime"  (Ca  2  H  O)  at 
the  bottom.  The  KaC  Oa  of  the  ashes  is  carried  by  the 
hot  water  down  through  lime,  and  the  reaction  is: — 

Ca  2  H  O    +    K,C  O3     =     2  K  H  O    +    Ca  C  O8 

•aye" 


130  CHEMICAL   PRIMER. 


If  no  lime  is  used,  of  course  the  lye  is  potassium  carbonate  (impure 
solution),  and  in  making  soap  from  K2C  03  we  have  (if  olive  oil  is  used) 
[Don't  try  to  remember  reaction.] 

3K.,C03     +      3H,0      +      2C3H53C18H3302     = 

X 
6KCj8H33O2    +    2C3H53HO     +    3  C  0.2 

soap  glycerine 

Soap  usually  contains  an  excess  of  the  alkali.     Home-made  soap  con- 
tains both  alkali  and  glycerine  and  is  very  variable  in  its  composition, 
containing  several  fat  acids  united  to  the  alkali.      Soap  is  insoluble  in 
salt-water  and  hence  separates  if  salt  be  added  to  the  "suds." 
"   I  \     ^^ — 

"Stearin"  candles  are  made  (chiefly)  of  stearic  acid  by  decompos- 
ing the  tallow  by  superheated  (285°)  steam. 

3H20    +    C3H53  C18H3502    =    3HC18H3502    -f    C3H53HO 

steam  tallow  stearic  acid  glycerine 

(stearin  caudles) 

There  are  two  great  classes  of  fixed  oils,  drying  oils  and 
non-drying  oils.  A  drying  oil  (as  linseed  oil,  i.  e.,  flax- 
seed  oil),  when  exposed  to  the  air,  oxidizes  to  a  hard  res  - 
inous  substance.  A  non-drying  oil  does  not  oxidize  to  a 
resinous  body  when  exposed  to  the  air,  but  instead  suffers 
a  fermentation  that  sets  the  acid  of  the  oil  free,  that  is, 
the  oil  becomes  "rancid."  For  instance,  the  purest  olive 
oil  is  not  entirely  free  from  nitrogenous  material,  and 
fungus  germs,  creeping  in,  cause  the  following  reaction : — 
C3H53  C18H3302  +  3  HS0  =  3  H  C18H3A  +  CaH53  H  O 

olive  oil  moisture  oieic  acid  glycerine 

from  air 

As  we  have  seen,  glycerine  (C3H5  3  H  O)  is  a  "by- 
product" in  the  manufacture  of  soap.  Glycerine  is 
classed  by  chemists  as  an  alcohol.  It  is  a  viscid,  sweet 
liquid,  a  good  solvent,  and  a  valuable  antiseptic.  It  is 
useful  in  dressing  wounds,  because  it  is  not  volatile,  but 
protects  from  the  air  and  keeps  the  part  moist.  Glycer- 
ine, treated  with  nitric  and  sulphuric  acids,  becomes  the 
fearful  explosive  nitro-glycerine  (C3H5  3  N  O3,  glyccryl 
nitrate). 


CHEMISTRY  OF  CLEANING.  131 

CHEMISTRY    OF    CLEANING. 

The  soaps  stand  first  in  the  list  of  cleansing  agents,  their  solution  in 
soft  water  (preferably  hot)  dissolving  or  forming  emulsions  with  oily 
substances.  The  sebaceous  glands  of  the  skin  secrete  oleaginous  matter 
to  keep  the  skin  soft  and  pliable  (there  is  also  oily  matter  in  the  perspi- 
ration). This  oil,  with  accompanying  "dirt,"  being  absorbed  by  the 
clothing  prevents  water  alone  from  cleansing  the  material,  as  "oil  and 
water  will  not  mix." 

Solutions  of  caustic  potash  and  caustic  soda  form  emulsions  with 
oils  even  more  readily  than  soaps  do,  but  they  corrode  the  skin  and  are 
apt  to  injure  the  cloth  as  well.  Dilute  solutions  are  used  to  clean  win- 
dow glass,  greasy  tins,  etc. 

Wood  ashes  (which  contain  potassium  carbonate)  are  used  with 
water  to  cleanse  bottles  and  coarse  utensils.  Solutions  of  potassium 
carbonate  operate  like  solutions  of  caustic  potash  only  with  much  less 
intensity. 

Ammonia  water  is  the  best  agent  for  cleaning  glass  and  (purified) 
for  cleansing  woolens  and  for  the  bath,  also  very  dilute  for  hair  brushes. 

Sal  soda  (washing  soda,  sodium  carbonate)  is  used  to  soften  hard 
water  (see  above)  and  also  is  useful  with  soft  water.  In  the  latter  case 
not  over  two  ounces  (first  dissolved]  should  be  added  to  a  large  tub  of 
water.  It  injures  the  skin  if  too  strong  rnd  does  not  cleanse  so  effect- 
ively. So-called  "washing  compounds"  are  composed  principally  of 
sodium  carbonate. 

Solutions  of  borax  are  excellent  to  cleanse  delicate  and  colored  fab- 
rics. They  also  soften  water  permanently  hard  (see  above). 

To  dissolve  oily  spots,  benzine  (a  volatile  oil  from  petroleum),  fresh, 
pure  turpentine,  alcohol,  and  ether  are  used.  Solid  absorbents  are  often 
to  be  preferred  to  remove  spots  from  paper,  carpets,  etc.,  such  as  mag- 
nesium carbonate,  powdered  soapstone,  and  buckwheat  flour.  These 
should  be  several  times  thoroughly  rubbed  into  the  carpet  or  upon  the 
paper  and  then  brushed  out  or  off  again. 

Grass  stains  are  removed  (while  fresh)  by  dissolving  in  absolute  alco- 
hol. Fruit  stains  are  washed  away  by  pouring  on  boiling  water,  or,  if 
this  fails,  by  solution  of  oxalic  acid. 

Iron  rust  (red)  is  best  removed  by  several  applications  of  hot,  very 
dilute  hydrochloric  acid,  soluble  chloride  of  iron  being  formed  by 
"change  of  partners."  Thoroughly  wash  afterward  with  water.  "Sol- 


132  CHEMICAL  PRIMER. 

uble  blues"  are  composed  principally  of  iron  ferrocyanide  (Prussian 
blue),  and  clothes  should  be  thoroughly  rinsed  to  remove  the  alkali,  or 
iron  rust  stains  appear  by  decomposition  of  the  "bluing." 

Ink  (black  iron  stains)  is  removed  by  solution  of  oxalic  acid,  chemi- 
cal reaction  by  "change  of  partners"  gives  iron  oxalate  and  tannic  acid. 
Immediately  and  thoroughly  wash  out  with  water  and  finally  with  very 
dilute  ammonia  water,  else  a  yellowish  tannic  acid  stain  is  left. 

Oxalic  acid  is  also  an  excellent  agent  for  cleansing  brass,  removing 
"shoe-leather"  stains,  etc. 

Fumes  of  burning  sulphur  (S  02,  which  see)  will  often  remove  col- 
ored spots  when  nothing  else  will. 

Acetic  acid  added  to  the  second  rinsing  water  will  restore  perfectly 
the  color  (if  from  "coal-tar"  dye)  of  bright  blue  flannels  or  other  fabrics 
that  fade  somewhat  in  washing,  because  the  soap  neutralizes  partially 
the  acid  contained  in  the  dye.  [See  "AMMONIA  WATER,"  page  62.] 

Coarse  scouring  agents  are  easily  obtained,  but  for  silver  and  arti- 
cles of  value,  the  best  polishing  agent  is,  perhaps,  precipitated  ckalk. 
Five  cents'  worth  of  quicklime  and  ten  cents'  worth  of  hydrochloric 
acid  by  the  process  of  EXP.  33,  will  precipitate  sufficient  to  last  for  a 
long  time.  The  water  used  should  be  filtered,  and  after  quicklime  is 
slacked,  the  clear  lime  water  should  be  carefully  drawn  off  by  siphon  so 
as  to  exclude  all  gritty  sediment.  After  precipitation  carefully  dry  and 
preserve.  Many  polishing  agents,  for  a  tablespoonful  of  which  twenty- 
five  cents  is  asked,  are  principally,  if  not  entirely,  precipitated  chalk. 
Most  ' '  tooth  pb^4££?"  %?^  simply  precipitated  chalk  .(colored  and  per- 
fumed). 

Volatile  oils  (or  Essential  oils)  are  of  vegetable  origin. 
They  exist  in  the  petals  of  flowers,  in  leaves  (of  mint),  -in 
seeds  (of  carraway),  in  rind  of  fruit  (of  orange,  lemon) 
and  in  the  root  (of  sassafras).  They  are  usually  obtained 
by  distilling  with  water  (passing  steam  over),  from  the 
part  of  the  plant  containing  them.  They  do  not  make 
soaps.  Their  "solution"  in  alcohol  is  called  an  essence. 
Adulteration  with  a  fixed  oil  is  easily  discovered  by  evap- 
orating on  white  paper  and  noticing  that  a  grease  spot  is 
left. 


ANTIDOTES.  133 


Oil  of  Turpentine  (Ci9H16  "spirits  of  turpentine")  is  obtained  from 
the  "pitch"  of  pines  by  distillation.  It  is  an  excellent  solvent,  dissolv- 
ing the  resins  to  form  varnishes.  A  large  class  of  volatile  oils  are  pure  hy- 
dro-carbons, many  having  the  same  empirical  formula  with  oil  of  turpen- 
tine, though  widely  different  in  properties. 

Of  a  second  class  Camphor  (CjdH160)  is  a  type,  as  oil  of  bitter  almonds, 
cinnamon,  spearmint,  etc.  These  all  contain  0. 

A  third  class  of  "strong  smelling"  volatile  oils  contain  S.  Ex:  Oil  of 
mustard,  horse-radish,  onion,  etc. 

A  resin  is  an  essential  oil  oxidized.  ("Rosin"  is  the  resin  of  tur- 
pentine.) A  balsam  is  an  oleo-resin,  i.  e.,  a  resin  dissolved  in  a  vola- 
tile oil,  or  a  volatile  oil  partially  oxidized.  If  a  balsam  is  distilled,  the 
essential  oil  passes  over,  leaving  the  resin  behind.  Shellac  is  a  resin 
obtained  from  lac,  the  juice  of  an  East  India  tree.  (See  APPENDIX.) 
Anil)er  is  a  fossil  resin. 

Gum  resins  are  milky  exudations  from  many  plants,  which  afterward 
solidify  in  the  air.  Gutta-percha  is  obtained  from  the  juice  of  an  East 
India  tree,  as  is  also  gum-benzoin,  the  chief  source  of  benzoic  acid 
(H  CTHdO,).  India-rubber  (caoutchouc)  is  the  solidified  juice  of  cer 
tain  tropical  trees.  Vulcanized  rubber  is  made  by  heating  the  rubber 
with  sulphur  (Goodyear's  patent). 


CHAPTER    XXXV. 


ANTIDOTES. 

TVhen  a  person  is  taken  suddenly  and  violently  ill  after  eating  some- 
thing, poisoning  may  be  suspected.  By  careful  attention  to  this  chap- 
ter it  is  more  than  possible  that  some  member  of  the  class  may  be  able 
to  save  a  human  life. 

A  poison  is  a  substance  which,  if  introduced  into  the 
animal  system,  may  produce  morbid  or  deadly  effects. 
We  give  antidotes,  either  (1)  to  get  rid  of  the  poison  at 
once  (by  means  of  an  emetic,  or  cathartic — a  mechanical 


134  CHEMICAL  PRIMER. 

antidote),  or  (2)  to  hinder  its  absorption  (as  when  we  give 
a  chemical  antidote  to  form  an  insoluble  compound  with 
the  poison — see  EXP.  12),  or  (3)  to  counteract  its  effect  (as 
when  we  give  stimulants  for  the  poison  of  serpent  bites, 
for  narcotic  poisons,  etc.). 

EXP.  138. — Shake  up  thoroughly  the  white  of  an  egg  in  a  bottle  half 
filled  with  water  and  filter.  The  filtrate  is  a  solution  of  albumen. 
Arrange  test  tubes  containing  very  slightly  acid  solution  of  soluble  com- 
pounds of  Hg  (corrosive  sublimate),  Cu.  Zn,  Sn,  Fe  (copperas),  Ag( ni- 
trate), [Pb  and  Ba]  respectively.  Into  each  let  fall  two  o^  three  drops 
of  albumen  solution.  Insoluble  compounds  of  albumen  and  the  metal 
(formula  too  complex  to  be  written)  are  precipitated.  [Notice  that  with 
Pb  and  Ba  compounds  the  precipitate  does  not  readily  appear  and  anti- 
dotes below  are  to  be  relied  upon.] 

Albumen  (milk,  flour  and  water,  and  especially  raw 
eggs)  is  an  excellent  chemical  antidote  for  most  metallic 
salts.  As  precipitates  are  not  absolutely  insoluble  in  the 
stomach,  they  should  be  immediately  removed  by  an 
emetic. 

The  best  emetic  is  the  common  one,  "mustard"  (a  tea- 
spoonful  in  a  cup  of — preferably  warm — water).  When- 
ever poisons  are  to  be  removed  by  an  emetic,  warm  water 
should  be  freely  drank  to  rinse  out  the  stomach  thor- 
oughly. Oils  (fats,  butter,  and  lard)  and  mucilaginous 
drinks  (as  flaxseed  tea)  are  always  beneficial  and  should 
be  freely  given  immediately,  and  for  treatment  afterward. 
In  general,  whatever  would  be  good  treatment  for  a 
burned,  bruised,  or  injured  skin,  is  good  treatment  for 
the  mucous  membrane  of  the  alimentary  canal,  burned 
or  irritated  by  some  poison. 

If  silver  nitrate  or  corrosive  sublimate  are  strony,  the  antidote  must  be 
given  within  a  few  seconds,  or  the  poison  will  have  done  its  worst,  and 
recovery,  if  it  takes  place  at  all,  must  depend  upon  after  treatment.  A 


ANTIDOTES.  135 

rather  large  dose  of  a  mild  cathartic  (as  castor  oil)  should  be  used  instead 
of  the  emetic  whenever  solution  of  either  sublimate  or  nitrate  has  been 
taken.  The  best  antidote  for  silver  nitrate  is  salt  and  water,  as  we  have 
inferred  from  EXP.  6,  though  albumen  is  about  as  good. 

If  the  other  metallic  salts  (except,  see  cyanides  below)  have  been 
swallowed,  especially  in  the  solid  state  (powder),  the  antidote  may  be 
given  later  (from  ten  to  twenty  minutes)  with  hope  of  its  doing  good. 
But  the  danger  rapidly  increases  with  the  lapse  of  time. 

Most  salts  of  Zii  and  Sb  (also  Cu  S  04)  are  fortunately  emetics  them- 
selves, but  if  vomiting  does  not  occur,  prompt  action  must  be  resorted 
to.  The  best  antidote  for  zinc,  copper,  or  iron  sulphate  is  a  careful  dose 
of  sodium  carbonate,  "washing  soda"  (followed  by  emetic). 

ZnS04    +    Na2C03     =    Na,SO4    +     Zn  C  03 

insoluble 

The  best  antidote  for  "arsenic"  (or  Sb)  is  fresh,  moist  ferric  hydrate, 
Fe2  6  H  0.  It  is  best  precipitated  when  needed  by  mixing  ferric  chlo- 
ride solution  (liquor  or  tincture)  with  slight  excess  of  dilute  ammonia 
water.  An  insoluble  ferric  arsenate  (Fe2  2  As  04)  is  formed  in  the  stom- 
ach. Chalk,  oil,  milk,  or  mucilaginous  drinks  may  be  given  to  envelop 
the  particles  of  As.2O3  mechanically,  if  it  has  been  taken  in  the  solid 
form;  but  the  thing  to  be  depended  upon  ordinarily  is  the  emetic,  followed 
by  purgative  (castor  oil). 

A  careful  dose  of  potassium  f errocyanide  is  a  good  antidote  for  copper 
compounds,  as  Cu.2  Fe  (C  N)6  is  insoluble  (give  emetic). 

Magnesium  sulphate  (Epsom  salt,  EXP.  12)  is  the  best 
antidote  for  lead  and  barium  compounds  (with  emetic). 

A  careful  dose  of  ammonium  carbonate  is  the  best  antidote  for  tin 
compounds  (with  emetic). 

Example: —  * 

SnCl2  +    (H4N),C03  +   H20    -    2H4NC1  +  Sn  2  H  O  +  C  Oa 

precipitate 


The  antidote  for  acids  (sulphuric,  nitric,  hydrochloric, 
etc.)  is  magnesium  carbonate  (see  REACTION,  CLASS  4), 
chalk,  lime-water,  or  soapsuds.  The  antidote  must  be 
given  within  a  few  seconds  if  the  acids  are  strong. 


136  ^.CHEMICAL   PRIMER. 

For  oxalic  acid,  lime-water  (Exp.  15,  or  chalk)  is  the  best  antidote. 
Prussia  acid  C^,C  N)  and  other  cyanides  require  stimulants,  as  cold 
douche  to  the  spine,  dilute  ammonia  water  inhaled  and  ammonium  car- 
bonate given  in  small  doses  (see  snake  poison  below).  If  prussic  acid  is 
strong  there  is  no  antidote.  Give  no  emetics  with  acids  (unless  acid 
is  very  dilute),  but  administer  oil  (olive)  freely. 


The  antidote  for  alkalies  (caustic  potash,  "lye,"  caus- 
tic soda,  etc.)  is  a  dilute  acid,  preferably  the  most  common 
one  vinegar  (acetic). 

KHO    +    HCaH303     =    KC2H302    +    H,0 

soluble  but 
harmless  salt 

Or  tartaric  acid,  "cream  of  tartar,"  citric  acid  (lemon  juice),  etc.  If 
these  are  not  at  hand  and  the  mineral  acids  are  given,  the  acid  must  be 
very  dilute  and  given  sparingly.  An  overdose  would  be  substituting  one 
poison  /or  another.  (For  caustic  baryta,  Ba  2  H  0,  or  for  lead  hydrate, 
see  above.) 

If  the  caustic  alkalies  are  strong,  the  antidote  must  follow  in  a  few 
seconds,  or  it  will  be  of  no  avail.  Give  HO  emetic  with  alkalies. 


For  narcotic  poisons  (as  opium,  morphine,  cholera 
medicines,  "soothing  syrups")  and  the  alkaloids  in  gen- 
eral, the  emetic  is  to  be  relied  upon  chiefly,  though  tan- 
nic  acid  (strong  tea  or  coffee)  may  be  given,  as  it  forms 
an  insoluble  compound  with  many  alkaloids. 

The  narcotic  poisons  require  in  addition  to  the  emetic,  stimulants 
(strong  coffee,  brandy,  careful  dose  of  ammonium  carbonate)  and  vigor- 
ous efforts  to  keep  the  patient  awake.  Strong  coffee  is  especially  useful  in 
cases  of  opium  poisoning,  as  it  acts  as  a  powerful  stimulant  to  the  nerve 
centers  affected  by  opium.  Aconite  calls  for  stimulants.  Strychnine  re- 
quires above  all  the  emetic,  also  the  inhalation  of  chloroform  or  ether  to 
check  spasms.  Patient  must  be  kept  as  quiet  as  possible. 

The  emetic  should  be  promptly  given  in  case  of  poisoning  by  un- 
healthy fish  or  meat.  Oils  should  follow  (and  paregoric  in  severe 
cases). 


ANTIDOTES.  137 


Phosphorus  poisoning  requires  the  emetic  and  mucilaginous  drinks 
,  with  magnesium  hydrate  (best  precipitated  when  needed  by  adding 
ammonium  hydrate  to  slight  excess  of  magnesium  sulphate  solution), 
followed  by  large  doses  of  the  cathartic  (purgative)  castor  oil. 

It  is  not  generally  known  that  "carbolic  acid"  (re- 
member that  this  is  not  an  acid  proper,  but  an  alcohol)  is  a 
more  dangerous  poison  than  strychnine.  Strychnine  kills 
"deliberately"  and  with  a  smaller  dose,  but  carbolic  acid 
does  its  work  quick.  Strychnine  gives  time  (10  to  even 
30  minutes)  to  hunt  up  antidotes,  or  call  a  physician ;  but  if 
a  teaspoonful  of  strong  carbolic  acid  is  taken,  usually  no 
remedy  will  save  a  life  after  twenty  seconds  have  elapsed. 
As  it  is  frequently  used  in  sick  rooms  for  bathing  pur- 
poses (diluted),  its  well  known  odor  is  no  protection  in 
such  cases.  Olive  oil  (butter,  lard,  etc.)  freely  given,  fol- 
lowed by  castor  oil  (cathartic)  is  its  best  antidote.  Give 
no  emetic. 

For  the  bite  of  poisonous  serpents  (poison,  a  powerful  sedative), 
stimulants,  as  alcoholic  liquors,  but  best  of  all,  ammonium  carbonate  (a 
teaspoonful  of  10  per  cent,  solution,  which  may  be  carried  in  a  small 
vial,  tightly  corked,  in  the  vest  pocket)  should  be  taken  within  a  few  sec- 
onds. The  dose  of  ammonium  carbonate  should  be  repeated  twice  at 
intervals  of  ten  minutes.  If  possible,  the  wound  should  be  immediately 
cauterized  (by  nitric  acid,  caustic  potash,  or  hot  wire),  or  ligature  put 
about  the  limb  above,  and  the  poison  sucked  out  from  the  wound  (the 
poison  is  harmless  in  the  stomach). 

NOTE. — The  pupil  will  notice  that  in  most  cases  of  poisoning  the 
emetic  is  given.  He  should  charge  his  memory  with  the  few  excep- 
tions, acids,  alkalies  (also  silver  nitrate,  corrosive  sublimate),  and  car- 
bolic acid,  and  give  emetics  in  all  other  cases.  To  receive  poisons  into 
an  empty  stomach  is  most  dangerous.  In  a  full  stomach  the  poison  is 
diluted  and  the  absorption  is  slow,  so  that  rapid  filling  of  the  stomach 
with  almost  any  liquid  food  would  be  better  than  nothing.  Especially 
would  milk  and  mucilaginous  drinks  be  useful  dilutents,  to  say  nothing 
of  their  soothing  action.  A  physician  should  be  called  in  all  cases  of 
serious  poisoning  to  direct  the  after-treatment. 


138  CHEMICAL   PRIMER. 

The  following  statements  about 'poisons  should  be  care- 
fully studied  and  observed  at  your  homes: — 

1.  Poisons  should  never  be  left  within  the  reach  of 
children. 

2.  They  should  be  kept  by  themselves,  apart  from  non- 
poisonous  medicines. 

3.  They  should  be  kept  plainly  labeled  as  poison. 

4.  Any  substance  in    an    unlabeled   bottle   should   be 
promptly  destroyed. 

5.  Whenever  a  poison  is  bought,  its  antidote  should  be 
bought,  placed  beside  it  and  plainly  labeled  (as  to  the 
proper  dose,  if  antidote  in  excess  would  be  injurious). 

6.  After  this  last  is  done  it  should  be  remembered  that 
"an  ounce  of  prevention  is  worth  a  hundred  pounds  of 
cure." 


MISCELLANEOUS  QUESTIONS. 

1.  Matter  exists  in  what  three  physical  states? 

2.  The  atomic  theory  divides  matter  how? 

3.  Atoms  of  different  elements  differ  in  what  three  essential  respects? 

4.  Define   compound   radical,  acid,  base,  salt,  precipitate,  reagent, 
filtrate,  sand  bath,  water  bath,  alkali,  sublimation. 

5.  What  is  "soda  water"?  Davy's  safety  lamp?  a  deliquescent  sub- 
stance? a  condenser?  a  pipette?  oil  of  vitriol?  aqua  regia? 

6.  How  much  mercury  in  150  grams  of  mercuric  sulphide  (use  tables)? 

7.  How  much  lead  will  be  required  to  make  250  kgs.  of  lead  carbon- 
ate ?     How  much  to  make  25  grams  of  Pb  0  ? 

8.  How  much  silver  nitrate  was  in  a  solution  from  which  30  gms.  of 
silver  chloride  was  precipitated? 

9.  Write  formulas  for  ferric  oxide,  cuprous  oxide,  mercuric  nitrate, 
ferrous  sulphide,  cupric  chloride,  aluminum  oxide,  mercurous  iodide, 
stannic  chloride,  ferrous  sulphate,  and  ferric  sulphate? 

10,  Reaction  when  calcium  carbonate  and  citric  acid  are  united. 

11.  Reaction  in  making  oxygen,  hydrogen,  carbon  dioxide,  hydrogen 
sulphide,  hydrochloric  acid,  and  sulphur  dioxide. 

$<V'r& 


MISCELLANEOUS  QUESTIONS.  139 

12.  How  many  litres  of  0  can  be  made  from  300  gms.  of  potassium 
chlorate?     (A  litre  of  H  weighs  .0896  gms.) 

13.  If  we  obtain  500  litres  of  C  (X,  how  much  calcium  carbonate  was 
used?    How  might  the  druggist  make  Cu  C4  H4  06? 

14.  Tell  what  you  know  of  S  O^  (3  lines),  of  oxygen,  of  nitrogen. 
Jell  what  you  know  of  H2S,  of  H,  of  C  0,,  of  Cl,  of  CJj__ 

16.  What  is  glass?     Ho w  annealed ?     How  colored?     How  etched? 

17.  How  might  you  tell  whether  or  not  a  white  powder  was  As203? 

18.  Give  Marsh's  test  for  "arsenic."     How  told  from  antimony? 

19.  What  is  an  alloy?  an  amalgam?  metal?  "paste"  diamonds? 

20.  What  three  methods  of  "mining  for  gold?"  and  tell  much  more 
about  each  than  you  find  in  this  Primer  (10  lines). 

21.  For  what  is  platinum  used?  phosphorus?  borax?  mercury? 

22.  What  would  you  do  if  you  had  taken  by  mistake  nitrate  of  Ag? 

23.  How  would  you  test  for  decomposing  organic  matter? 

24.  Why  can  some  metals  be  cast,  while  others  cannot? 

25.  What  is  "white  lead,"  and  how  made?     What  is  mosaic  gold? 

26.  What  is  the  antidote  for  lead  acetate?  barium  hydrate?  carbolic 
acid?  corrosive  snblimate?  oxalic  acid?  phosphorous? 

27.  Give  Bessemer's  process  for  making  steel.      Leblanc's  process  for 
Na_,C  03.     How  would  the  druggist  make  calcium  citrate? 

28.  What  is  "galvanized  iron?"    "tinware?"    quicklime?   plaster  of 
Paris?  quartz?  a  "base  metal"?  an  oxidizing  agent? 

29.  What  is  fusible  metal?  indelible  ink?  gelatin?  leather? 

30.  Difference  between  water-slacked  and  air-slacked  lime? 

31.  Give  reaction  in  making  soft  soap  (use  TABLE);  hard  soap. 

32.  How  is  brown  sugar  refined  ?    Name  five  prominent  alkaloids. 

33.  Reactions  in  alcoholic  and  acetic  fermentations  (CCHI206  sugar). 

34.  Why  is  soap  wasted  when  hard  water  is  used  in  washing? 

35.  What  is  a  resin?  rosin?  a  balsam?  tincture?  essence?  soap? 

36.  What  would  you  do  if  one  had  taken  an  overdose  of  morphine? 

37.  In  what  cases  of  poisoning  should  no  emetic  be  given? 

38.  What  makes  the  bread  "rise?"     Explain  fully. 

39.  Xame  all  the  antiseptics  mentioned  in  this  book. 

40.  Name  the  disinfectants;  the  anaesthetics;  the  bleaching  agents. 


140  CHEMICAL  PRIMER, 


APPENDIX, 


SECTION     A. 


NORMAL   SALTS,  ACID    SALTS,  ETC. 

A  normal  salt  (old  name  neutral  salt)  is  one  which  is 
formed  by  replacing  all  the  replaceable  hydrogen  of  the 
acid  by  a  positive  element  or  grouping. 

EXAMPLES 

H2  C4  H4  06  =  hydrogen  tartrate  =  acid. 

K.2  C4  H4  06  =  potassium  tartrate  —  normal  salt. 

NOTE. — Hitherto  by  salts  have  been  meant  normal  salts. 

An  acid  salt  is  one  which  is  formed  by  replacing  only 
part  of  the  replaceable  hydrogen  of  the  acid  by  a  positive 
element  or  grouping. 

EXAMPLE. 

H2C4H4O6  =  hydrogen  tartrate  —  acid. 

TT  TC  r  TT  O    -  -    /  hydr°gen  potassium  tartrate  \    _       .,      ,. 
[KC4H406~    |    or  acid  potassium  tartrate    /    ' 

Acid  salts  usually  turn  blue  litmus  red,  but  this  is  by  no  means 
universal.  In  EXP.  39,  if  one-half  as  much  sodium  nitrate  be  taken, 
with  strong  sulphuric  acid,  an  acid  salt,  instead  of  a  normal  salt,  results. 

NaN03    +    H,S04    =    H  Na  S  04    +    H  N  03 

acid 
sodium 
sulphate 


APPENDIX.  141 


In  general,  by  adding  an  excess  of  the  acid  (which  is  the  same  as 
taking  less  of  the  other  substance),  an  acid  salt  may  be  obtained.  Acid 
salts,  as  a  rule,  react  with  carbonates  like  acids,  that  is,  forming  a  salt 
(normal),  water,  and  carbon  dioxide,  as: — 

2HKC4H406    +    K2C03    =    2  K2C4H406    +    H2O    +    C  02 

acid  salt  carbonate  normal  water  carbon 

salt  dioxide 

A  double  salt  is  one  which  is  formed  by  replacing  part 
or  all  of  the  replaceable  hydrogen  of  the  acid  by  two  pos- 
itive elements  or  groupings. 

EXAMPLE. 

H2C4H406  =  tartaric  acid. 

K  Xa  C4H406  —  potassium  sodium  tartrate  =  double  salt. 
("Rochelle  salt") 

H3P  04  —  phosphoric  acid. 

H  Xa  H4  N  P  04  =  hydrogen  sodium  ammonium  phosphate  = 
double  salt  (microcosmic  salt).  A  double  salt  may  be  at  the  same  time 
an  acid  salt,  like  the  last. 

A  double  salt  may  be  formed  by  an  acid  salt  of  one  metal  acting  on 
the  carbonate  of  the  other,  thus: — 

/ 
Na,C  0;1   +   2  H  K  C4H406   =    2  K  Na  C4H406  +   H20  +  C  O, 

sodium  acid  double  water  carbon 

carbonate  potassium  salt  dioxide 

tartrate 

Acids  containing  one,  two,  three,  etc. ,  atoms  of  replaceable  hydrogen 
are  said  to  be  respectively  monobasic,  dibasic,  tribasic,  etc. 

H  X  03  =  monobasic  acid. 

H2S  04  =  dibasic  acid. 

H3P  04  =  tribasic  acid. 

H4Si  04  —  tetrabasic  acid. 

NOTE. — A  tribasic  acid  may  form  two  acid  salts,  as: — 

H^Xa  P  04  =  dihydrogen  sodium  phosphate  =  acid  salt. 

H  Xa2P  04  =  hydrogen  disodium  phosphate  =  acid  salt. 

A  basic  salt  is  one  which  may  be  formed  by  replacing 
one  or  more  hydrate  groupings  of  the  base  by  a  negative 
grouping.  [This  definition  is  a  narrow  one,  covering  most 


142  CHEMICAL   PRIMER. 

but  not  all  basic  salts.  It  may  be,  however,  that  basic 
salts  are  molecular  compounds  of  the  hydrate  (or  oxide)  of 
the  metal  with  the  metallic  salt,  the  hydrate  uniting  after 
the  analogy  of  water  of  crystallization.] 

EXAMPLE. 

Pb  2  H  0  —  lead  hydrate  =  base. 

Pb  H  O  N  03  =  lead  hydro-nitrate  —  basic  salt. 

A12  6  H  0  —  aluminum  hydrate  =.  base. 

A12  (H  0)2  Si  04  —  aluminum  hydro-silicate  =  basic  salt. 

Bi  3  H  0  =  bismuth  hydrate  =  base. 

tr  /TT  rk\  AT  r\  (basic  bismuth  nitrate,  "subnitrate  of  bismuth," 

0)2J\  03  -:       uged  krel    in  medicine 


Sulph-  and  selen-acids  and  salts.  In  all  formulas  for 
ternaries  thus  far  explained,  oxygen  has  been  the  last  ele- 
ment. It  is  supposed  to  be  principally  a  linking  or  connect- 
ing element.  Now  there  are  a  few  other  dyad  elements 
that  can  perform  this  office  of  linking,  especially  sulphur 
and  selenium.  To  write  the  formula  for  a  sulph-  or  a 
selen-acid  or  salt,  the  same  reference  table  may  be  used, 
only  sulphur  or  selenium,  as  the  case  may  be,  must  be 
substituted  atom  for  atom,  in  place  of  oxygen. 

EXAMPLE. 

K.2C  03  =•  potassium  carbonate  —  salt. 

K2C  S3  =  potassium  sulpho-carbonate  =  sulph-salt. 

Ag3  As  Q^  =  silver  arsenate  —  salt. 

Ag3  As  S4  —  silver  sulph-arsenate  —  sulph-salt. 

K3  Sb  03  =  potassium  antimonite  —  salt. 

K3  Sb  S3  =  potassium  selen-antimonite  =  selen-salt. 

H3  As  S4  =  hydrogen  sulph-arsenate  —  sulph-acid. 

NOTE.  —  Instead  of  sulph-,  thio-  (Greek  tluon,  sulphur)  is  used  by  some 
chemists,  as  K^C  S3  =  potassium  thio-carbonate. 

The  sulph-  and  selen-acids  and  salts  are  few  compared  to  those  con- 
taining oxygen. 


APPENDIX.  143 


SECTION     B. 


THE     ALLOY,    SPECTRUM    ANALYSIS,    AND 
SYSTEMS   OF   CRYSTALLIZATION. 

The  most  important  alloys  (with  their  usual  proportions)  are:— 

Aluminum  Bronze Cu  (9)  Al  (1) 

Bell-metal Cu,  (9)  Sn  (2) 

Brass Cu  (2)  Zn  (1) 

Bronze Cu  (95)  Sn  (4)  Zn  (1) 

Coin  (gold) Au  (90)  Cu  (9)  Ag  (1) 

Coin  (silver) Ag  (9)  Cu  (1) 

Fusible  Metal Bi  (see)  Pb  Sn 

German  Silver Cu  (5)  Zn  (2)  Xi  (2) 

v — brass — ' 

Hard  Solder Cu  (1)  Zn  (1) 

-  Pewter Sn  (4)  Pb  (1) 

Phosphor-bronze Cu  (88)  Sn  (10)  P  (1.5)  Pb  (.5) 

Shot Pb  (99.5)  As  (.5) 

Soft  Solder Pb  (1)  Sn  (1) 

Type-metal Pb  (70)  Sb  (20)  Sn  (10) 


The  spectroscope,  next  to  the  balance,  is  the  most  useful  instrument 
for  original  chemical  research.  It  consists  of  a  prism,  mounted  upon 
a  stand,  carrying  a  tube  with  fine,  adjustable  slit,  through  which  light 
(the  rays  being  made  parallel  by  a  lens)  falls  upon  the  prism.  The 
light,  refracted  by  the  prism,  is  received  by  a  small  telescope,  which 
magnifies  the  spectrum  ("rainbow,"  if  solar  spectrum, i.  e.,  if  light  is 
sunlight)  before  it  reaches  the  eye.  The  spectrum  of  the  sun  has  dark 
lines  (Fraunhofer's  lines),  crossing  it  at  right  angles  all  along  from 
the  red  to  the  violet  portion,  but  at  irregular  intervals.  The  relative 
position  of  these  lines  has  been  accurately  determined. 


144 


CHEMICAL  PRIMER. 


If,  instead  of  sunlight,  the  light  from  the  sodium  flame  (Exp.  130) 
enters  the  slit,  no  colored  bands  from  red  to  violet,  as  in  the  solar  spec- 
trum, are  seen.  Instead,  the  spectrum  is  totally  dark  except  a  brilliant 
yellow  line  (double)  crossing  the  spectrum  where  before  (in  solar  spec- 
trum) was  the  dark  line  D  (double).  If  the  light  of  the  potassium  flame 
enter  the  slit,  three  lines  appear  on  the  dark  spectrum:  a  bright  pur- 
plish line  at  (what  was  before)  the  violet  end,  and  at  the  other  end  two 
red  lines — one  somewhat  bright,  the  other  very  faint. 


SPECTRA    OF 


R 

ed 

§>         1 
§  Yeljlow     Gr 

o        1 

et 

n                Bl 

ue    Indigo    Vio 

lot 

ABC 


E    b 


Sun  with 

few  dark  lines 

shown. 


Sodium. 


fellow  line 


Potassium. 


ish  line 


Strontium. 


Red 


All  the  other  metals  and  non-metals  have  characteristic  spectra,  but 
some  substances  require  more  heat  than  the  flame  of  the  Bunsen's  burner 
to  volatilize  them.  For  these  the  electric  flame  is  used.  With  a  small 
spectroscope,  however,  the  student  can  easily  obtain  the  spectra  of  Na, 
K,  Ba,  Sr,  and  Ca,  whos 3  chlorides  are  volatilized  in  Bunsen's  or  alcohol 
flame.  [See  Fig.  43.  For  some  laboratory  spectroscopes,  spectra  are 
reversed  and  Fig.  43  must  be  turned  upside  down  to  represent  the  view.] 


APPENDIX.  145 


Many  rare  metals  have  been  discovered  by  means  of  the  spectroscope 
(caesium,  rubidium,  thallium,  indium,  etc. ).  By  it  the  light  of  the  heav- 
enly bodies  reveals  the  presence  in  these  orbs  of  many  elements  com- 
mon upon  the  earth.  (Celestial  Chemistry.) 


Most  chemical  substances,  when  they  pass  from  the  liquid  to  the  solid 
state,  assume  some  definite  form  and  are  said  to  crystallize.  (See 
EXP.  34  and  connection. )  It  has  been  found  possible  to  arrange  all 
crystals  in  six  systems,  according  to  the  arrangement  of  their  sides  and 
angles  around  certain  imaginary  axes,  intersecting  at  the  center  of  the 
crystals.  These  axes  are  shown  on.y  in  Plates  I  and  n  of  Fig.  44. 

1.  Regular  System. — Three  axes  all  equal  and  all  at  right  angles. 
Plates  i,  u,  and  in.     Ex. :  Common  salt,  alum,  garnet. 

2.  Hexagonal  System. — Four  axes,  three  equal  and  in  one  plane, 
making  angles  of  60°,  and  one,  longer  or  shorter,  at  right  angles  to  the 
plane   of  the  other  three.     Plates   iv  and  v.     Ex. :  Sodium  nitrate, 
quartz,  and  ice. 

3.  Quadratic  System. — Three  axes  all  at  right  angles,  and  one 
shorter  or  longer  than  the  other  two.     Plates  vi  and  vu.     Ex. :  Potas- 
sium ferrocyanide  and  tin  dioxide. 

4.  Rhombic  System.— Three   axes   all   unequal   and   all  at  right 
angles.     Plates  vm  and  ix.     Ex. :  Potassium  nitrate,  barium  sulphate, 
and  sulphur,  crystallized  from  solution  in  carbon  bisulphide. 

5.  Monoclinic  System.— Three  axes  all  unequal.      Two  cut  each 
other  obliquely,  and  one  is  at  right  angles  to  the  plane  of  the  other  two. 
Plate  x.     Ex. :  Sodium  carbonate,  sodium  phosphate,  ferrous  sulphate, 
borax,  cane-sugar,  and  sulphur/rom/M^'on. 

6.  Triclinic  System.— Three  axes,  all  unequal  and  all  oblique. 
Plates  xi  and  xn.     Ex. :  Copper  sulphate,  manganese  sulphate,  boracio 
acid  and  potassium  bichromate. 

Certain  substances,  like  S,  crystallize  in  two  systems,  and  are  said 
to  be  dimorphous.  A  very  few  substances  are  trimorphous.  Anything 
without  crystalline  form  is  amorphous  (as  plastic  sulphur).  Different 
substances  that  crystallize  in  the  same  form  are  isomorphous  (as  com- 
pounds of  the  halogens  with  the  same  metal).  A  crystalline  body  splits 
more  readily  in  a  certain  direction  than  others.  This  splitting  is  called 
cleavage.  The  powder  of  a  crushed  or  scratched  mineral  is  called  its 
stntk. 


146  CHEMICAL  PRIMER. 


Fits.  44. 


APPENDIX.  147 


SECTION     C. 


DYEING. 

EXP.  1. — Dissolve  a  little  aniline  blue  (C.^H16  (C6H5)3N3)  in  alcohol, 
and  dip  clean,  white  silk  thread  into  it.  Expose  the  thread  to  the  air, 
the  alcohol  evaporates  and  leaves  the  blue  color  adherent  to  every  fiber 
of  the  silk. 

Aniline  (CeHjH.^X)  is  a  volatile,  oily  liquid;  colorless,  when  pure, 
but  by  oxidation,  action  of  chemical  agents,  etc.,  aniline  black,  red  (ma- 
geiita),  orange,  yellow,  green,  blue,  and  violet  (rnauve)  are  produced. 
The  reaction*  in  the  formation  of  the  wonderful  "aniline  dyes"  are  by 
far  too  complex  for  introduction  here. 

EXP.  2. — Upon  fine  zinc  filings  in  a  beaker  place  a  minute  quantity 
of  blue  indigo,  add  a  moderately  strong  solution  of  potassium  hydrate 
(potash)  and  heat. 

(a)— Zn     +     2  K  H  O     =     K  Zn  02     -f     H, 

nascent 

(b)-H,    +    Clt;H10X20.,     =     C16HlaX20, 

reducing  blue  indigo  white  indigo 

agent 

Dip  a  piece  of  clean,  white  woolen  (or  cotton)  cloth  in  the  solution  of 
white  indigo  and  expose  to  the  air,  blue  indigo  is  formed  in  its  fibers  by 
oxidation  and  adheres,  that  is,  is  a  "fast"  color  (does  not  wash  out  in 
warm  soap-suds). 

C,«H12XA    +     0     =     C)r,HU)X,02    +     H,0 

white  indigo  blue  iiidigo  evaporates 

EXP.  3. — Divide  a  dilute  (1  per  cent.)  solution  of  picric  acid 
(C6HjX30le)  into  two  portions.  Into  one  dip  a  piece  of  woolen  yarn, 
into  the  other  dip  cotton  yarn.  Remove  each  and  wash.  The  first  is 
dyed  a  brilliant  yellow,  the  second  is  not  colored. 


148  CHEMICAL  PRIMER. 

Substances  that  dye  directly  are  called  substantive  colors.  Coloring 
substances  may  form  colored  compounds  with  the  fibers  of  the  cloth,  or 
(usually)  may  merely  adhere  to  the  fibers.  Cotton  and  linen  often 
require  different  treatment  from  wool  or  silk  to  produce  the  same  color, 
and,  in  general,  are  dyed  with  more  difficulty. 

EXP.  4. — Divide  a  solution  of  alum  into  two  parts.  To  the  first  add 
H^N-H  0,  a  flocculent  precipitate  of  aluminum  hydrate  (A12  6  H  0) 
falls.  To  the  second  add  a  few  drops  of  solution  of  cochineal  (carmine 
ink),  and  then  H4  N  H  0.  AL,  6  H  O  is  precipitated  as  before,  and 
slowly  settles,  carrying  the  coloring  matter  down  with  it,  forming  a 
66  lake." 

Some  other  metallic  hydrates  (or  oxides),  especially  of  tin  and  of  iron, 
have  the  same  great  affinity  for  organic  coloring  matter.  The  com- 
pounds they  form  with  coloring  matters  are  called  lakes.  The  hydrates 
also  have  "great  affinity  for"  (adherence  to)  the  fibers  of  cloth.  Every 
one  knows  that,  though  "dirt"  can  be  readily  washed  from  a  white 
apron,  iron  rust  is  removed  with  great  difficulty  (only  by  chemical 
agents — see  CHEMISTRY  OF  CLEANING).  Hydrates  (or  salts,  from  which 
the  hydrates  may  be  produced)  that  have  a  great  affinity  for  coloring 
matter  and  also  for  the  fiber  of  cloth,  are  called  mordants,  and  a  color 
that  will  not  dye  directly,  but  needs  a  mordant,  is  called  an  adjective 
color. 

Coloring  by  means  of  mordants  is  the  usual  method.  The  most 
common  mordants  are  copperas,  tin  salts,  and  alum.  The  cloth  is  first 
dipped  into  a  solution  of  the  mordant  and  then  into  the  dye.  Of  course 
different  mordants  produce  different  colors,  when  used  with  the  same 
dye.  The  mordants  may  be  applied  by  means  of  stamps  (or  rollers)  and 
any  pattern  (as  for  calico)  brought  out  in  the  various  colors. 

EXP.  5. — Boil  a  piece  of  Fe  S  04  in  nitric  acid  (90  per  cent.),  till 
red  fumes  cease  to  appear;  dilute  and  filter.  Preserve  filtrate  (Fe23  S  04, 
"persulphate  of  iron").  Dip  clean  silk  into  this  ferric  sulphate  (mor- 
dant) and  leave  for  a  few  minutes.  Drain,  and  immerse  in  solution  of 
potassium  ferrocyanide  (dye).  It  is  colored  a  deep  blue  (Prussian 
blue). 
2Fe83S04  +  3K4Fe(CN)6  =  6K2S04  +  (Fe,)2 3  Fe  (C  N)6 

Mordant  dye  ferric  ferrocyanide 

Prussian  blue 

The  reactions  of  the  organic  dyes  with  their  mordants  are  too  complex 
to  be  written  out.  Indeed,  many  of  them  are  unknown.  The  most 
common  coloring  substances  are  madder  (coloring  principle  alizarin,  now 
made  artificially  from  coal-tar),  cochineal  (dried  insects  from  cactus  of 
Central  America,  coloring  principle,  carmine),  logwood,  indigo,  litmus, 
etc.  (See  DYEING,  in  cyclopaedia.) 


APPENDIX.  149 


SECTION     E>. 


ADDITIONAL   EXPERIMENTS. 

HYDROGEN  AND  OXYGEN. 

EXP.  1.— Repeat  EXP.  30  with  a  test-tube  of  the  right  size  and  the  H 
flame  "sings."  It  sets  the  column  of  air  in  vibration  within  the  test- 
tube. 

EXP.  2.— Ignite  a  small  jet  of  H  by  holding  in  it  platinum  sponge 
(previously  heated  to  expel  absorbed  gases  which  hinder  the  action). 

EXP.  3. — Place  a  sounding  tuning-fork  in  a  jar  of  H;  the  tone  is  raised 
to  a  shrill  pitch. 

EXP.  4.— Burn  a  minute  jet  of  0  [driven  by  reservoir  (1)  from  holder 
(3)  as  in  frontispiece]  in  a  jar  of  H,  quickly  igniting  the  jet  by  passing 
through  burning  H  at  the  mouth.  (See  NOTE  EXP.  26. )  [Bore  hole  in 
receiver  (1)  with  rat-tail  file  moistened  frequently  by  turpentine.] 

EXP.  5. — Connect  H  and  O  holders  with  oxy-hydrogen  blowpipe 
(Fig.  17),  and  igniting  the  H  first,  turn  on  the  0.  Place  small  piece  of 
fine  Pt  wire  (fused  into  glass  holder,  Fig.  40)  in  the  flame.  It  melts. 
[The  rubber  cork  in  the  H  holder  should  be  well  oiled  and  firmly  bound 
down  by  strong  twine  fastened  to  shoulder  of  the  bottle.  The  H  snould 
be  drawn  into  a  test-tube  over  water  and  tested  before  it  is  burned  in 
the  blowpipe.  If  it  burns  quietly  after  taking  fire  it  is  safe  to  ignite 
jet.  If  it  burns  explosively,  it  is  mixed  with  air  and  must  not  be  ignited. 
The  holder  is  first  filled  completely  with  water  and  the  H  (from  genera- 
tor as  FRONTISPIECE  2)  or  O  pressing  backward  expels  the  water,  the 
reservoir  being  kept  so  that  the  water  in  it  shall  be  only  about  a  deci- 
meter above  the  water  in  the  holder.  Common  illuminating  gas  may  be 
used  instead  of  hydrogen  with  practically  the  same  results.] 


150  CHEMICAL   PRIMER. 

EXP.  C. — Into  a  tube  closed  at  one  end  (through  which  Pt  wires  are 
fused  vvith  the  internal  ends  almost  but  not  quite  touching)  filled  and 
inverted  over  mercury,  put  2  cu.  cm.  of  O  and  4  cu.  cm.  of  H  and  ex- 
plode by  electric  current.  The  mercury  rises  and  with  the  water  above 
completely  fills  the  tube  (except  perhaps  a  bubble  of  gas,  which  is  the 
result  of  inaccurate  measurement).  Composition  of  water  is  proved  by 
synthesis,  as  nothing  is  found  dissolved  in  the  water. 


CHLORINE. 

EXP.  7. — Mix  in  the  dark,  dry  Cl  and  dry  H  in  a  stout  bottle,  and 
with  care  explode  by  sudden  exposing  to  direct  sunshine.  H  Cl  fumes  are 
formed. 

EXP.  8. — Fill  jar  with  H  Cl  gas  and  make  hydrochloric  acid  fountain 
similar  to  ammonia  fountain  of  Fig.  22. 


SULPHUR. 

EXP.  9.— Repeat  EXP.  92  and  afterward  immerse  rose  in  dilute  sul- 
phuric acid.  The  color  is  restored  to  nearly  the  original  tint. 

EXP.  10. — Place  in  a  small  flask  (provided  with  safety  tube  as  in  Fig. 
25,  or  as  in  H.2S  generator  in  FRONTISPIECE  2)  pieces  of  copper  wire  (or 
"drop  copper")  and  add  as  much  strong  H,  S  04  as  will  not  quite  cover 
the  copper.  Carefully  heat  until  gas  begins  to  be  evolved  and  then 
regulate  heat;  else  the  liquid  froths  from  too  violent  reaction. 

Cu    -f    2H2S04    =    CuSO,    +    2H20    +    S  O2 

Pass  through  small  con- 
denser and  connect  conden- 
ser with  apparatus  (S  02 
condenser)  shown  in  Fig. 
45,  which  is  immersed  in  a 
freezing  mixture  (ice  and 
salt).  S  0.2  is  easily  con- 
densed by  "co/c/  "  to  a  liquid. 
Turn  stop-cocks  and  pre- 

serve.     Wire  stop-cocks  (Fig.  46)  on  rubber  connectors  (boiled  in  paraf- 

fine)  may  be  used  in  place  of  glass  stop-cocks. 


APPENDIX. 


151 


S  02  may  also  be  condensed  in  strong  glass  tube  (drawn  to  a  point  at 
Sne  end)  by  pressure  of  a  plunger  with  close-fitting,  greased  rubber 
head.  When  pressure  (at  lo3)  reaches  one  and  one-half  atmospheres, 
drops  appear  on  the  side,  and  liquid  S  O2  gathers  in  the  lower  part  of 

the  tube.  If  plunger  is  quickly 
withdrawn  a  part  is  frozen  (by 
cold  produced  by  sudden  evap- 
oration] into  a  snow-white  solid. 

Place  \vater  in  a  small  plati- 
num or  other  thin-walled  dish 
and  pour  around  it  a  little 
liquid  S  O2.  Blow  with  bel- 
lows to  hasten  evaporation  of 
S  02.  The  r  .pid  vaporization 
produces  a  cold  ( — 50°)  so  great 
Fig.  46— Spring  Stop-Cock.  (absorbs  so  much  heat)  that  the 

water  is  quickly  frozen.  Mercury  may  be  frozen  if  used  instead  of 
water.  (It  must  not  be  put  in  platinum  dish — why?)  If  S  O2  be  evap- 
orated in  the  receiver  of  an  air-pump,  a  part  will  be  solidified  (frozen) 
forming  snow-like  solid. 


PHOSPHORUS. 


EXF.  11.—  In  a  flask  place  a  few  minute  pieces  of  P  and  cover  with 
strong  solution  of  caustic  potash.  Displace  the  air  in  the  flask  by  pass- 
ing H  through  the  stopple  of  flask  until  the  bubbles  caught  over  pneu- 
matic tube  of  water  burn  quietly.  Clos«  by  wire  spring  (Fig.  46)  the 
rubber  tube  through  which  H  is  admitted  and  heat  flask. 


3KHO 


3H20    =    3KH2P02    -f    H3  P 


The  hydrogen  phosphide  (phosphine)  takes  fire  because  vapor  of  liquid 
P2  H4  is  present  and  the  beautiful  white  rings  of  smoke  ascend.  (Pure 
H3  P  is  not  spontaneously  inflammable. )  Remove  heat  and  pass  H  as 
before  and  throw  away  poisonous  liquid. 

Caution.— Perform  in  a  well  ventilated  room  and  immediately  open 
doors  and  windows  after  the  experiment. 


152 


CHEMICAL  PRIMER. 


EXP.  12.— The  best  test  for 
the  element  phosphorus  (paste, 
rat  poison)  is  that  of  distilla- 
tion. Place  suspected  sub- 
stance in  flask,  add  dilute  sul- 
phuric acid  and  pass  vapor 
through  a  glass  condenser  (set 
in  a  perfectly  dark  box  painted 
with  black  pigment  on  the  in- 
side) and  into  water  (Fig.  47). 
Look  into  the  box  by  means  of 
a  small  tube,  while  the  head, 
like  the  photographer's  in  ad- 
justing his  camera,  is  covered 
by  dark  cloth  or  shawl.  The 
vapor  is  distinctly  pho-sphorescent 
if  even  a  minute  quantity  of  free 

Fig.  47.  A-from  flask.  B-conden?er.  CD-  P  *  P^ent  in  substance  The 
cold  water,  a  b  c  d— rubber  tubes  to  ex-  test  determines  with  absolute 
dude  light.  certainty  whether  free  phos- 

phorus is  present.  In  cases  of  poisoning  this  test  must  be  applied 
without  long  exposure  to  the  air,  as  P  in  presence  of  organic  matter  and 
air  rapidly  oxidizes. 

ARSENICUM  AND  ANTIMONY. 

EXP.  13. — Place  a  small  piece  of  clean  copper  wire  in  arsenical  solu- 
tion acidulated  with  hydrochloric  acid,  and  boil.  (H  N  O3  must  not  be 
present. )  Arsenicum  is  deposited  on  the  copper.  Wash,  carefully  dry 
and  heat  slowly  in  closed  glass  tube;  octahedral  crystals  of  As2  03  are 
deposited.  (Reinsch's  test.) 

EXP.  14. — Generate  hydrogen  by  heating  to  near  the  boiling  point  a 
strong  solution  of  Na  H  0  and  Zn. 

Zn    +    2NaHO     =     Na2Zn02    +    H2 

Add  a  few  drops  of  a  solution  of  "arsenic,"  and  pass  gas  through 
wash-bottle  of  lead  acetate  solution  to  remove  accidental  traces  of 
H2  S;  spread  over  mouth  of  wash-bottle  filter  paper  moistened  with 
Ag  N  08. 

H3    +    As    =    H3As 
H8As  +  3  H20  +  6  Ag  N  Oa  =  H3As  03  +  6  H  N  03  +  Ag6 


APPENDIX.  153 


The  free  silver  turns  the  paper  purplish-black.     (Fleitmann's  test  dis- 
tinguishes arsenicum  in  presence  of  antimony. ) 


GOLD. 

EXP.  15.  —  To  a  solution  of  an  auric  salt  (Au  C13)  add  H2  S.  A 
brown  precipitate  of  Au2  S3  falls,  soluble  in  (H^X),  S.,. 

2  Au  C13    -f    3  H.S    =    Au,  S3     +     6  H  Cl 

EXP.  16.—  To  solution  of  salt  of  gold  (Au  C13)  add  ferroMS  sulphate, 
and  set  aside  for  awhile. 

2AuCl3    +    6FeSOi    =    Au2    +     Fe2Cl6    +     2Fe.23SO< 

ferrou*  free  ferric  ferric 

sulphate  gold  chloride  sulphate 

Boil  precipitate  of  free  gold  in  H  Cl,  mix  with  equal  bulk  of  borax 
and  fuse  in  strong  blowpipe  flame.  A  "button"  of  pure  gold  is  obtained. 

EXP.  17.  —  Add  a  few  drops  of  solution  of  stannous  and  stannic  chlo- 
rides (Cl  water  put  into  Sn  C1.2  gives  Sn  C14)  to  dilute  solution  of  Au  C13, 
a  purplish,  finely-divided  precipitate,  "purple  of  Cassius"  (composition 
doubtful),  falls.  The  same  precipitate  is  slowly  obtained,  if  tin  foil  is 
placed  in  solution  of  Au  C13. 


SILVER. 

EXP.  18.  —  Sink  a  small  piece  of  unsized  paper  into  Xa  Cl  solu- 
tion for  five  minutes.  Dry.  In  a  dark  box  dip  it  beneath  Ag  X  03 
solution  for  one  minute.  Lay  this  "prepared  paper"  upon  a  flattened 
leaf  which  lies  upon  glass.  Cover  with  an  old  book  cover  and  expose 
the  glass  to  sunlight.  A  white  "picture"  of  the  leaf  is  formed.  Remove 
paper,  and  in  dark  box  "fix"  by  dipping  into  sodium  hyposulphite 
(Xa2  S  02  or  hot  Xa  Cl  solution)  for  five  minutes.  Wash  by  dipping 
alternately  for  three  minutes  at  a  time  into  sodium  hyposulphite  and 
then  into  clear  water.  If  glass  is  used  in  place  of  paper  to  hold  the 
Ag  X  03  and  Xa  Cl,  a  "negative"  of  the  leaf  is  formed. 


MERCURY. 


EXP.  19.  —  In  a  solution  of  salt  of  Hg  place  a  clean  (by  H  X  O3  and 
afterward  H.20)  copper  wire.  It  is  soon  coated  with  a  mirror  of  Hg, 
more  apparent  if  dried  by  blotting-paper  and  gently  burnished  with  soft 


154  CHEMICAL   PRIMER. 

cloth.  An  equivalent  amount  of  copper  passes  into  the  solution  to  take 
the  place  of  the  displaced  Hg.  Cut  off  the  mirrored  end  of  the  wire, 
and.  placing  in  closed  glass  tube,  heat.  Hg  distills  and  globules  of  the 
metal  gather  upon  the  sides  of  the  tube. 

In  almost  any  solution  containing  soluble  compound  of  Hg,  it  may  be 
detected  by  this  test.  No  test  for  Hg  should  be  considered  complete 
unless  metallic  globules  are  obtained.  A  lens  will  often  reveal  the 
globules,  if  the  amount  of  mercury  is  exceedingly  small. 

EXP.  20. — To  mercurows  nitrate  add  K  I,  green  mercurows  iodide 
(Hg.2I2)  falls.  To  mercuric  nitrate  add  K  I,  red  mercuric  iodide  (Hg  I2) 
falls  (Exp.  10).  Wash,  dry,  place  in  cold  tube,  and  sublime.  Hg  I2 
condenses  on  the  sides  of  the  tube  in  yellow  crystals;  rub  crystals  with 
stick,  they  change  to  the  original  red.  This  change  of  color  may  be  re- 
peated indefinitely. 


COPPER. 

EXP.  21.— Into  a  solution  of  a  copper  salt  (as  Cu  S  04)  put  a  piece  of 
clean  iron.  It  is  coated  with  copper,  an  equivalent  amount  of  iron 
passing  into  solution. 

Cu  S  04     +     Fe     =     Fe  S  04     +     Cu  (deposited  on  iron). 

EXP.  22. — Add  H4  N  H  O  to  cupric  solution,  a  characteristic  blue 
precipitate  soluble  in  excess  of  H4N  H  0  is  obtained. 

Cu  2  N  O3    +     2  H4  N  H  0     -    2  H4  N  N  03    +     Cu  2  H  0 

precipitate 


ALUMINIUM. 

EXP.  23. — Thoroughly  char  on  platinum  foil,  bread  tiontaining  alum. 
Pulverize  and  boil  in  dilute  H  Cl,  filter,  neutralize  with  ammonium 
hydrate;  a  fine  precipitate  of  A126  H  0  (having  very  distinct  surface  as 
it  settles)  falls.  Set  aside;  minute,  distinct  crystals  appear. 


CALCIUM. 

EXP.  24. — Heat  in  oxy-hydrogen  blowpipe  flame  the  sharpened  end 
of  a  stick  of  quicklime,  a  dazzling  light  is  emitted  ("lime  light").  (Do 
not  look  steadily  at  the  light.) 


APPENDIX. 


155 


BARIUM    AND    STRONTIUM. 


iiT.  47.— Green  Fire. 


EXP.  25. — Pulverize  sepa- 
rately with  great  care 
Ba  "2  X  03  (oxidizing  and  col- 
oring agent),  K  Cl  03  (oxidiz- 
ing agent),  and  gum  shellac 
(C  and  H  principally,  com- 
bustible body).  Add  one  drop 
of  strong  H  Cl  to  the  barium 
chlorate  powder  and  mix  care- 
fully and  thoroughly  equal 
bulk  of  each  upon  piece  of 
paper.  Place  on  wire  gauze 
in  shoal  pan  and  ignite,  using 
the  paper  as  a  fuse.  It  gives 
green  fire. 


EXP    26.— Repeat  EXP.   25,  using  Sr  2  N  03  instead  of   Ba  2  N  08. 
Red  fire  results. 


Fig.  45. 


ORGANIC    CHEMISTRY. 

EXP.  27.— Repeat  sugar  test, 
EXP.  132.  Albumen,  if  present, 
must  be  removed  by  boiling  and 
filtering.  Earthy  phosphates 
should  be  removed  by  adding 
caustic  potash  to  alkaline  reac- 
tion and  filtering.  The  caustic 
potash  used  must  have  been  kept 
in  the  best  Bohemian  glass  bottles, 
and  not  in  bottles  containing  lead: 
otherwise  Pb  0  falls  and  is  mis- 
taken for  Cu2  0. 


Fi-.  49. 

A  mere  yellow  color  is  not  suffi- 
cient, there  must  be  an  actual  precipitate,  without  pro- 
longed boiliny. — Perform  the  same  experiment  without  heating,  but  set 
test-tube  away  for  twelve  hours  instead.  The  Cu.j  0  is  precipitated. 

EXP.  28. — Fill  a  test-tub©  entirely  full  of  clear  animal  secretion  con- 
taining sugar;  add  a  small  quantity  of  yeast  and  close  the  mouth  of  the 
test-tube  by  a  rubber  cork,  through  which  runs  a  fine  glass  tube  nearly 


156  CHEMICAL  PRIMER. 

to  the  bottom  of  the  test-tube  (Fig.  48).  Set  in  a  warm  place  for  ten  or 
twelve  hours.  The  C  02,  produced  by  the  fermentation,  collects  in  the 
top  of  the  test-tube,  and  forces  the  liquid  out  of  the  fine  glass  tube. 
This  Fermentation  Test  is  an  excellent  one  for  sugar  in  animal  secretions. 
EXP.  29. — Take  the  sp.  gr.  of  a  liquid  containing  sugar  before  fermen- 
tation and  after;  every  "degree"  lost  corresponds  to  the  presence  of  21 
mgs.  of  sugar  in  10  cu.  cm.  of  the  liquid  ("1  grain  of  sug  r  per  fluid 
ounce").  That  is,  if  urinometer  (Fig.  49)  shows  1050  before  and  1030  after 
fermentation,  there  are  420  mgs.  of  sugar  in  10  cu.  cm.  of  the  liquid 
(or  20  grains  per  fluid  ounce).  This  is  Roberts'  quantitative  test. 


EXP.  30. — Add  a  small  quantity  of  albumen  (Exp.  138)  to  distilled 
water,  or  to  animal  secretion  filtered.  Upon  pure,  colorless,  nitric  acid, 
in  test-tube  of  small  diameter,  slightly  inclined,  allow  the  liquid  to 
trickle  from  a  pipette.  A  sharp,  white  zone  appears  at  the  junction  of 
the  two  liquids,  not  dissipated  by  heat.  This  is  an  excellent  test  for 
albumen.  (Urates,  if  present  in  excess,  produce  a  somewhat  similar 
white  zone,  but  the  zone  is  dissipated  by  heat  much  less  than  the  boil- 
ing point.  Be  careful  not  to  mistake  the  mere  mixing  of  the  zone  by 
boiling,  for  dissipation.  If  liquid  is  highly  colored,  of  course  albumen 
will  be  tinged  with  the  color.) 

EXP.  31. — Add  to  animal  secretion  containing  albumen,  a  few  drops 
of  strong  caustic  potash,  and  filter.  Add  nitric  acid  to  distinct  acid 
reaction  and  boil.  White  coagula  appear  (greenish,  if  bile  is  present, 
brownish-red,  if  blood  is  present).  A  good  test  for  albumen.  (Rarely 
it  is  necessary  to  allow  to  cool,  and  then  boil  the  second  time. ) 

EXP.  32.— Precipitate  a  large  amount  of  albumen  from  solution  (Exp. 
138)  in  distilled  water,  by  adding  nitric  acid  and  boiling.  Filter,  wash, 
and  dry  over  water-bath.  Arrange  a  dozen  narrow,  deep  test- 
tubes  nearly  filled  with  the  acid  water.  Carefully  weigh  out,  by  means 
of  a  fine  pair  of  scales  (any  chemist  will  allow  the  use  of  his  scales),  5, 
10,  15.... 55,  60  mgs.  of  albumen  powder,  and  placing  in  each  test- 
tube  respectively,  allow  about  three  times  as  long  for  settling 
because  of  dryness  of  albumen.  By  means  of  a  very  fine,  sharp 
file,  carefully  mark  the  height  of  the  precipitated  albumen.  Reserve 
test-tubes  for  quantitative  testing  for  albumen.  For  example :  If  5  cu. 
cm.  of  liquid  to  be  tested  were  placed  in  first  test-tube,  and  the  precip- 
itated albumen  reaches  to  the  mark  on  the  test-tube,  1  mg.  of  albumen 
is  present  in  every  cu.  cm.  of  the  liquid.  This  is  a  very  convenient 
approximate  quantitative  test  for  albumen. 


APPENDIX.  157 


TESTS  FOR  THE  ALKALOIDS. 

EXP.  33. — Upon  small  piece  of  a  salt  of  morphia  on  glass  slide,  place 
a  drop  of  water.  Warm  till  salt  is  dissolved.  Place  beside  it  a  minute 
drop  of  strong  neutral  solution  of  perchloride  of  iron  (Fea  C16).  Bring 
together  by  glass  rod,  a  dirty-blue  color  results. 

EXP.  34. — To  solution  of  a  salt  of  morphia,  add  sodium  carbonate 
solution  A  white  precipitate  falls,  crystalline  if  solution  is  dilute. 
Test  as  in  EXP.  33  above. 

EXP.  35. — Moisten  a  salt  of  morphia  with  nitric  acid;  an  orange-red 
color  results. 

EXP.  36. — To  a  few  drops  of  an  aqueous  solution  of  opium,  add  drop 
by  drop  neutral  solution  of  perchloride  of  iron.  A  red  solution  of  mec- 
onate  of  iron  is  formed,  not  destroyed  by  addition  of  corrosive  sublimate 
solution. 

EXP.  37.  — Heat  morphia  on  platinum  foil,  it  burns  and  leaves  no  res- 
idue. 


EXP.  38. — To  solution  of  quinine  (or  of  its  salts)  slightly  acidulated 
with  H  Cl,  add  fresh  chlorine  water,  and  then  ammonia  water;  a  green 
coloration  is  produced. 

EXP.  39.— Repeat  EXP.  38,  but  add  potassium  ferrocyanide  before 
adding  ammonia;  an  evanescent  red  coloration  appears. 

EXP.  40. — Upon  quinine  (or  its  salts)  let  fall  a  few  drops  of  strong 
sulphuric  acid.  It  dissolves,  producing  faint  yellow  color. 

EXP.  41. — Repeat  EXP.  40,  with  quinine  that  has  been  adulterated 
with  the  cheaper  salicin,  a  deep  red  color  appears. 

EXP.  42. — Dissolve  quinine  in  cold  nitric  acid;  a  colorless  solution  is 
formed.  Heat,  it  turns  yellowish. 

EXP.  43. — Heat  quinine  on  platinum  foil,  no  residue  is  left. 


EXP.  44. — Place  a  small  particle  of  strychnia  on  a  white  dish  and 
near  it  a  small  piece  of  potassium  bichromate.  Add  a  drop  of  strong 
sulphuric  acid  to  each  and  after  a  few  moments  bring  the  bichromate 
upon  the  strychnine  drop  with  a  glass  rod;  a  vivid  purple  color  ap- 
pears, rapidly  fading  into  yellowish  red. 


158  CHEMICAL   PRIMER. 

EXP.  45. — Upon  a  drop  of  dilute  solution  of  strychnia  on  glass  slide, 
place  drop  of  potassium  sulphocyanide;  a  white  precipitate  appears. 
Examine  with  microscope  and  tufts  of  auricular  crystals  are  seen. 

EXP.  46. — Add  strong  sulphuric  acid  to  a  crystal  of  strychnia  and 
heat  over  water -bath;  it  is  unaffected. 

EXP.  47. — Add  strong,  cold  nitric  acid  to  a  crystal  of  strychnia;  it  is 
unaffected.  Heat,  it  turns  yellow  but  does  not  dissolve. 

EXP.  48. — Place  a  small  frog  in  water  containing  traces  of  strychnia 
and  in  two  or  three  hours  (sooner  if  stronger  solution  is  used)  a  slight 
jar  throws  him  into  the  characteristic  tetanic  spasms. 


EXP.  49. — Place  a  drop  of  tincture  of  aconite  upon  the  skin,  a  tin- 
gling sensation  is  produced  followed  by  prolonged  numbness. 


EXP.  50.  —  To  a  solution  of  atropia  (belladonna)  add  a  few  drops  of 
perchloride  of  gold;  a  yellow  precipitate  appears.  —  One  drop  of  very 
dilute  aqueous  solution,  applied  directly  to  interior  of  eyelid,  powerfully 
dilates  the  pupil. 


NOTES. 

(1)  Uncrystallizable  substances  (colloids)  in  solution  diffuse  slowly 
through  a  septum,  as  parchment  paper;  while  crystallizable  substances 
(crystalloids)  diffuse  rapidly.  If  a  small  hoop,  covered  with  parchment 
paper  and  filled  with  mixed  solution,  be  floated  upon  water  the  crys- 
talloids pass  rapidly  through  while  the  colloids  principally  remain  be- 
hind. This  process  of  separation  is  called  Dialysis.  The  so-called 
"dialyzed  iron"  is  the  colloid,  the  basic  oxy-chloride  of  iron.  (2)  See 
larger  works  as  to  properties  of  C  02,  as  to  condensation  of  H;  and  late 
scientific  journals  as  to  whether  shellac  may  not  be  principally  an  ani- 
mal product.  (3)  The  soap  bubble  experiment,  page  51,  sometimes 
fails  because  too  strong  acid  is  used,  and  acid  moisture  being  carried 
over  in  the  draft  makes  the  bubble  brittle.  But  inquiries  as  to  "what's 
the  matter?"  is  a  fruitful  source  of  chemical  knowledge. 


QUANTITATIVE  TEST  FOB  CAEBON  DIOXIDE  IN  SCHOOLEOOMS  (AS  AN  INDEX  TO  THE 
AMOUNT  OP  POISONOUS  "ANIMAL  VAPOE"  PEESENT). 

The  proportion  of  carbon  dioxide  is  generally  estimated  by  volume  and  on  a  scale  of 
so  many  parts  in  10,000  of  air.  In  pure  out-door  air  there  are  about  4  parts  of  carbon 
dioxide  :n  10,000  of  air.  In  the  school-room  the  proportion  should  never  rise  above  8 
parts.  Examination  of  the  following  reactions  and  explanations  will  reveal  the  sim- 
plicity of  the  test. 

Ba2HO     +    H,C204,  2H2O    =    BaC,04     +    4H20 

barium  crystallized  barium  water 

hydrate  oxalic  acid  ox.ilat  • 

171  126 

Ba2HO     +    C02     =     Ba  C  03    -f     H20 

171  44 

In  neutralizing  power. 

126  gms.  of  cr.  oxalic  acid     =     171  gms.  of  barium  hydrate. 


44  gms.  of  C  02 
therefore  44  gms.  of  C  02       = 


171 
126 


of  cr.  oxalic  acid. 


1  gm.  C  O2  =  2.863   +  gms.,  or  2863  mgs.  of  cr.  ox.  acid. 

If  we  weigh  carefully  2863  mgs.  of  cr.  oxalic  acid  (not  deliquesced)  and  dissolve  in 
1,000  cu.  cm.  (litre)  of  distilled  water,  then  1  cu.  cm.  of  that  "standard"  solution  will 
equal  <in  neutralizing  power)  1  milligram  of  carbon  dioxide.  [Keep  solution  in  dark 
bottle.  Prepare  new  solution  of  aci  i  every  two  or  three  weeks.  The  most  important 
thin.;  in  the  test  is  that  the  oxalic  acid  solution  be  fresh  and  made  from  perfect  crys- 
tals.] 

We  then  make  a  solution  of  barium  hydrate  dissolving  about  5  gms.  in  a  litre  of 
water. 

Suppose  a  jug  (bottle)  with  tight-fitting  rubber  cork  holds  4,155  cu.  cm.  (carefully 
measured*,  which  jug  we  fill  from  the  air  of  the  schoolroom  by  means  of  a  small  bel- 
lows (blown  a  sufficient  number  of  times,  say  25),  and  take  temperature  of  the  room 
at  the  same  time  as  20°.  Into  this  we  pour  from  a  sp.  gr.  bottle  (holding  with  the 
8;lass  stopper  in,  100  cu.  cm.)  100  cu.  cm.  of  the  barium  hydrate  solution  and  shake 
thoroughly  at  intervals.  We  now  fill  the  burette  (FRONTISPIECE  5)  with  the  "standard" 
solution  of  oxalic  acid,  to  a  point  a  little  above  0  and  run  it  down  carefully  drop  by 
drop  to  the  0  point  vre  isely.  Measuring  from  barium  hydrate  solution  (by  means  of 
another  sp.  $:r.  bottle  holding  50  cu.  cm.)  50  cu.  cm.  we  pour  it  into  a  clean,  wide- 
mouthed  bottle,  rinse  with  distilled  water  and  pour  this  in  also.  We  now  add  a  little 
blue  litmus  solution  (or  brown  solution  of  turmeric).  Open  the  but  ette  and  alluw  the 
acid  to  run  slowly  (the  last  drop  by  drop)  into  the  wide-mouthid  bottle  containing  the 
50  cu.  cm.  of  barium  hydrate  solution.  It  takes  say  24.5  cu.  cm.  of  acid  to  neutralize 
the  alkali— when  the  last  drop  needed  13  added  the  litmus  suddenly  turns  red  (tur- 
meric turns  yellow).  Now  carefully  fill  the  second  sp.  gr.  bottle  (holding  50  cu.  cm.) 
with  the  solution  taken  from  the  jug  containing  the  schoolroom  air.  Again  fill  the 
burette  as  before  and  see  how  many  cu.  cm.  of  the  acid  are  required  to  neutralize  the 
50  cu.  cm.  taken  from  the  jug.  We  find  in  every  case  it  requires  less,  because  the 
carbon  dioxide  in  the  jug  has  already  neutralized  part  of  it.  It  requires,  say,  22  cu. 
cm.  of  the  acid.  24.5  cu.  cm.  —  22  cu.  cm.  =  2.5  cu.  cm.  But  from  equations  above 
we  know  that  1  cu.  cm.  of  the  acid  corresponds  to  1  mg.  of  carbon  dioxide;  therefore 
as  we  poured  out  only  one-half  of  the  alkali  to  test  there  were  5  mgs.  of  carbon  dioxide 
in  the  jug.  From  table  we  see  that  1  mg.  of  carbon  dioxide  at  20°  occupies  .544470  cu. 
cm.  of  space,  therefore  5  mgs.  occupy  2  72235  cu.  cm.  The  question  then  becomes, — 
If  in  4055  (4155-100)  cu.  cm.  of  air  there  are  2.72235  cu.  cm.  of  carbon  dioxide,  how 
much  carbon  dioxide  in  10,000  cu.  cm.  of  air  ?  We  have  the  proportion 

4,055:    10,OOO ::    2.72235: 

from  which  we  obtain  6.7  parts  in  10,000  as  the  answer,  that  is,  the  room  is  fairly 
ventilated. 

Space  occupied  by  1  mg.  ofC  O2  at  different  temperatures  (barom.  760  mm.). 


Degree 

Cubic  Cm. 

Degree 

Cubic  Cm. 

DtL'iee 

Degree 

Cubic  Cm. 

Co 

.507306 

g 

.546328 

% 

2 

.559336 

15 

59 

J  35178 

22 

71.6 

.548186 

29 

84.2 

.561194 

16 

60.8 

.537037 

23 

73.4 

.550044 

30 

86. 

.563052 

17 

626 

.538895 

24 

75.2 

.551903 

31 

87.8 

.564910 

18 

64.4 

.540753 

25 

77. 

.553761 

32 

89.6 

.568769 

19 

66.2 

.542611 

2o 

78.8 

.555619 

33 

91.4 

.568627 

20 

63 

.544470 

.  27 

80.6 

.557477 

34 

93.2 

.570485 

35 

95. 

.572343 

A  factor  can  be  worke  1  cut  f  >r  each  jug  used  and  for  each  temperature,  so  that  by 
a  simple  multiplication  of  the  difference  shown  by  the  burette  the  result  is  obtained. 
[The  factor  of  this  jug  for  this  temperature  is  2.68+.  Dif.  by  burette  2.5  x  2.68+  = 
6.7+.]  Any  bright  pupil  can  master  the  test  in  a  few  hours  and  can  apply  it  in  a  few 
minutes  by  using  factors.  The  test  can  be  made  after  school  or  before  school  the  next 
day.  Such  tests  regularly  reported  would  do  much  to  awaken  an  interest  in  having 
a  proper  system  of  ventilation. 


160 


CHEMICAL   PRIMER. 


SECTION     E. 


METRIC  SYSTEM. 


LINEAR. 


10  Millimetres  (mm.)  =  1  Centimetre  (cm.) 
10  Centimeties  =  1  Decimetre  (d  cm.) 

10  Decimetres  —  1  Metre  (m) 

10  Metres  =  1  Dekametre 

10  Dekametres  =  1  Hektometre 

10  Hektometres          =  1  KiL-metre 


WEIGHTS. 

10  Milligrams  (ing.)  =  1  Centigram  (cgm.) 
10  Centigrams  =  1  Decigram  (dc;.) 

10  Decigrams  =  1  <•  ram  (gm.) 

10  Grams  =  1  Dekagram 

10  Uekagrams  =  1  Hektogram 

10  Hektograms          =  1 

1,000  Kilograms        -=  1  Metric  Ton  (M.  T.) 


CAPACITY. 


10  Millilitres 
10  Centilitres 
10  Decilitres 
10  Litres 
10  Dekalitres 
10  Hektolitres 


=  1  Centilitre 
=  1  Decilitre 
=  1  Litre 

=  1  Dekalitre 
=  1  Hektolitre 
=  1  Kilolitre 


1  Metre  (meter)  =  39.37  inches. 
Litre  =  61  cubic  inches. 

Litre  =  1  cubic  decimetre. 

Gram  =  15.43  grains. 

Gram  =  weight  of  1  cu.  cm.  of 

water  4') 

Kilogram      =  2  1-5  Ibs. 
Kilogram       •=  weight  of  1  cu.  dcm.(litre) 
of  water  (4°) 


1  sq.     I 
cm. 


1  Decimetre  ••  10  Centimetres. 

REFERENCE  TABLE  No.  2— CONTINUED. 

NEGATIVE  GROUPINGS. 
=  metaphosphate 
C5  H9  05  =  valerianate 
C  N  O  =  cyanate 
C  H  0,  =  formate 
C4  H7  02  =  butyrate  (butter) 
C7H50U  =  benzoate 
VN  02  =  nitrite 


C3H403  =  lactate 
C5H2N403   =  urate 
B4  07   =  tetraborate  (borax) 
Mn  04   —  manganate 
Mn2  08  =   permanganate 
Cru07   =  bichromate 


C4H305  =  malate 

C7  H  0T  =  meconate  (opium) 

C7H3O5   =  gallate 

C27  H19  017   =  tannate 

Fea  (C  N)12  -  ferricyanide 


*§  r 
|  { 


-  ferrocyanid* 


POSITIVE  GROUPING. 


APPENDIX.  161 


SUGGESTIONS  FOR  STUDENTS  USING  THE  ANALYTI- 
CAL CHARTS. 

In  most  schools  this  should  be  a  volunteer  class  and  the  work  extra, 
put  in  after  school  hours  or  on  Saturdays.  Be  sure  you  want  to  do  the 
work  before  you  undertake  it.  Don't  talk  to  others  while  at  work,  ex- 
cept in  rare  instances  so  far  as  quietly  to  obtain  information.  Don;t 
"fool"  in  the  laboratory  and  report  those  who  insist  upon  doing  it,  that 
they  may  be  promptly  removed  from  the  class.  Have  no  false  honor 
about  this,  for  the  nonsense  of  one  may  vitiate  all  accurate  woik  for  a 
class. —Reserve  a  portion  of  the  original  solution  to  begin  upon  again  in 
case  of  accident,  also  for  special  tests.— Common  drink  ing  water,  boiled, 
cooled,  and  filtered,  usually  answers  for  all  work  with  the  first  two 
Groups;  but  distilled  water  must  be  used  for  the  other  Groups,  and  is 
better  for  all  reagents. — Precipitate  thoroughly  each  Group,  but  on  t.  ? 
other  hand  avoid  much  excess  of  the  precipitating  reagent. — Evaporate 
filtrates  if  they  become  too  dilute.  A  coal-oil  stove  makes  a  cheap 
source  of  heat  for  evaporation. — Avoid  breathing,  to  any  great  extent, 
fumes  of  hot  H  Cl,  H4N  H  O,  H  N  O3,  aqua  regia,  etc.  Hold  dishes  at 
arms'  length  while  pouring  such  liquids.  Under  a  gas  chimney  with 
flame  at  base  to  increase  draft,  is  the  proper  place  to  generate  noxious 
fumes;  but  such  work  may  be  easily  done  upon  a  shelf  by  open  window 
with  slight  outward  draft.— Make  (H4N)2S  by  passing  H2S  into  dilute 
H4X  H  0  (10%)  till  saturated  and  then  add  ^ual  volume  of  HHN  H  O. 
Digest  this  with  a  little  S  and  filter  to  make  (H4N)2S2  (yellow],  or  expose 
(H4N).^S  to  air  for  sufficient  time. — A  convenient  H2S  generator  is 
shown  in  FRONTISPIECE  (2).  The  middle  bulb  contains  Fe  S.  A  test- 
tube  with  small  hole  in  bottom  (containing  a  little  broken  glass  upon 
which  is  Fe  8),  lowered  into  wide-mouthed  bottle  of  dilute  H.2S  04  and 
test -tube  closed  by  perforated  rubber  stopple  through  which  is  glass 
tul>e  connected  with  rubber  tube  held  by  spring,  Fig.  46,  makes  a  cheap 
H  .S  apparatus. — Fig.  50  shows  a  convenient  reagent  bottle  with  pipetted 
stopple.  Take  test-tube  to  bottle  to  add  reagent,  not  bottle  to  test- 
tulie,  and  be  careful  not  to  stir  up  any  sediment  which  may  have  fallen 
in  rase  drinking  water  has  been  used. — Fig.  51  represents  a  system  of 
rapid Jtttratio*.  The  stream  of  Mrater  must  be  regulated.  The  logger 
the  tube  a,  the  more  rapid  the  filtering.  Chamber  b  must  l>e  air-tight 
at  top.  Pt  (foil)  funnel-shaped  tip  must  support  filter  paper  at  bottom, 
and  the  wet  edges  of  filter  paper  must  be  pressed  firmly  against  upper 
part  of  funnel.  A  partial  vacuum  is  formed  in  chamber  b  and  flask  <v — 
For  color  of  precipitates,  additional  tests,  etc.,  see  EXP.  97  and  INDEX, 
also  have  a  work  on  Qualitative  Aitoiysu  upon  th<>  desk  for  reference. 


162 


CHEMICAL    PRIMER. 


I.       Add  H  Cl  (15  per  cent.)  drop  by  drop  till  upon  settling  no  pre- 
cipitate falls Filter. 


Precipitate Hg2Cl2,  Ag  Cl,  Pb  C12,  insolu- 
ble chlorides.  Wash  twice  with  cold  water 
(Fig.  7),  drain,  and  washing  from  paper  with 
wrash-bottle  into  beaker,  boil  for  one  minute, 
and Filter  while  hot. 


Filtrate. . .  soluble 
chlorides  of  other 
metals,  Cu,  Bi,  Fe, 
Mg. . .  .also  traces  of 
Pb  C12. 


Precipitate Hg2  C12,  Ag  Cl.     Wash 

with  hot  water  to  remove  all  of  the  Pb  C12, 
if  Pb  has  been  found,  drain,  and  add  warm 
H4N  H  0  (15%),  pouring  it  through  two 
or  three  times.  The  ammonia  water  dis- 
solves Ag  Cl  but  reacts  with  Hg2  C12. 


Precipitate  Filtrate  ...  Ag  Cl 

H2IS  Hg2  Cl  =  amido-  Add  H  N03(15%) 
mercurous  chloride  black.  to  acid  reaction. 
(If  no  black  color  ap-  Ag  C1  is  reprecip- 
pears  no  mercury  in  om  itated  because  its 
form  is  present.)  Dis- solvent  is  neu. 
solve  in  beaker  a  portion  tralized  Filter 
in  five  or  six  drops  of  . .  ,.wash.  . .  .and 
aqua  regia  and  evaporate  fuse  on  charcoal 
carefully  nearly  to  dry- as  in  Exp  113 
ness,  dilute  and  test  so-  obtaining  silver 
lution  of  HgCl2  (1)  byglobule  with  no 
EXP.  19  APPENDIX,  or  incrustation  on 
(2)  by  adding  a  drop  oficoai 

Sn  C12  and  white  Hg2ClJ ! 

is  precipitated.  Add  excess  of  Sn  Cl.,  and 
gray  metallic  Hg  falls  forming  into  globule 
if  boiled  with  H  Cl. 


Filtrate PbCl2 

(Hot  water  dissolves  Pb  C12) 

( 1 )  Place  drop  of  filtrate  on 
glass   and    slowly   evaporate 
white  needle-shaped  crystals 
of  Pb  C12  are  left,  touch  with 
drop  of  K  I  solution,  yellow 
Pb  I2    appears.      Divide   fil- 
trate into  three  portions  and 
to  first  portion 

(2)  Add  H2S  04  (15%),  white 
Pb  S  04  falls.        To    second 
portion 

(3)  Add  K2Cr207  (3%)  yellow 
Pb  Cr  O4  falls.     To  third  and 
largest  portion 

(4)  Add  (H4N\S,  black  Pb  S 
falls.    Fuse  with  little  K2C  03 
on  charcoal  in  reducing  (near) 
flame  of  the  blowpipe.    Lead 
globule    is    obtained    with 
yellow  incrustation  on  char- 
coal.     Globule  is  malleable. 
(Biand  Sb  are  brittle.) 


II.  Evaporate  filtiate  from  first  group  to  small  bulk,  add  ten  drops  of  strong  H  Cl 
and  evaporate  carefully  nearly  to  dryness.  Dilute  with  hot  E^O  and  pass  JH^S  sas 
through  hot  solution ...  .Filter. 

Precipitate insoluble  sulphides  of  Hg  (ic),  Cu,  Pb,  Bi,  I  Filtrate  soluble  chlo- 

Sn,  Sb,  As  (Au,  Pt).  Wash  with  hot  water digest  ten  I  rides  of  other  metals, 

minutes  in  (H4N)oS2  (yellow) Filter  |  Co,  Fe,  Mn,  Mg,  etc. 

Precipitate .  ..Hg,  Cu,  Pb,  Bi  (sulphides).  I  Filtrate. .  .Sn,  Sb,  As  (Au,  Pt)  tulphides. 
Wash  with  hot  water,  add  strong,  boiling  Add  dilute  H  Cl,  sulphides  are  reprecipi- 
hot  H  N  03,  pouring  it  on  several  times,  tated filter,  drain  well,  boil  in  little 


Ppt  Hg. 
Dissolve  in 
aqua  regia  and 
test  as  in  First 
Group. 

Filtrate  Cu,  Pb,  Bi. 
Add  five  drops  strong  H2S  64 
and  boil  down  to  small  bulk. 
Pb  gives  white  precipitate. 
Filter  

Precipitate...  As,  yel- 
low. Wash  and  confirm 
by  digesting  in  (H4N)2 
C  O3  and  reprecipitat- 
ing  in  filtrate  As2  03 
by  H  Cl,  otherwise  S 
from  decomposition  of 
(H4N)2S2  may  be  mis- 
taken for  As. 

Filtrate..  Sn,Sb. 
Dilute  with  water 
and  place  a  small 
piece  of  clean  Zn, 
and  of    clean  Pt 
wire  in  the  solu- 
tion.    Sb  forms  a 
distinct     black 
stain  upon   Pt. 
ve  in   hot  dilute 
naporate  to  drv- 

Precipitate  Pb  |      v\\ 

trate  Bi,  Cu. 
Filter. 

Add  H4N  HO. 

Ppt  .  .Bi  white.    Fuse 
with  K2  C  Oa   on  char- 
coal... brittle  globule. 

Filtrate..  Cu,  deep 
blue  solution.  ..test 
by  EXP.  21,  APP. 

Wash  Pt  wire.  Disso] 
H  N  Og,  remove  wire,  < 

ii ess,  add  few  drops  dilute  H  Cl  and  pass  H2S.  Orange-yellow  precipitate,  turns  gray- 
ish-black by  EXP.  110.— After  Zn  has  all  dif solved,  filter  and  add  drop  of  Hg  CL 
white  precipitate  of  Hg2  Cl;  indicates  Sn. — (Au  and  Pt  rarely  occur  in  solution  ) 


ANALYTICAL    CHARTS. 


163 


III.  To  filtrate  from  second  group  add  H4N  H  0  till  alkaline  (avoid 
excess),  then  add  H4N  Cl  and  (H4]V)2S  and  warm  gently  for  five  min- 
utes  Filter. 


Precipitate,  .sulphides  of  ?si,  Co,  Fe,  Mn,  Zn,  hydrates 
of  Cr  and  Al.  Wash  with  very  dilute  (H4N)2S  and  then 
with  water.  Add  dilute  H  Cl  breaking  bottom  of  paper 
and  washing  through  into  beaker. .  .  .Filter. 


Filtrate. . 
soluble  com- 
pounds   of 


Precipitate  .  .  .Ni,  Co 
(sulphides).  Fuse  a  por- 
tion in  borax  head— blue 
indicates  Co.  Violet 
when  hot  and  brown 
when  cold  indicates  Ni 
alone.  If  b.ith  are  pres- 
ent Co  overpowers  Ni 
colors.— Dissolve  the  re- 
maining ppt.  in  few 
drops  of  aqua  regia,  evap- 
orate to  dryness,  dissolve 
in  few  drops  of  water, 
add  a  little  CoCl2  and 
evaporate  on  white  pa- 
per. Cr reen  indicates  Ni. 


,  metals  of  iv  and  v  Group. 

riitrate Fe,  Mu,  cr,  Zn,  Al.     Add  tew  drops  of  H  N  Oj 

evaporate  carefulty  neatly  to  dn  ness,  dilute  slightly,  add 
K  H  O  till  strongly  alkaline,  boil  carefully  3  minutes. Filter. 


l'pt....Fe,  Mn.Cr.  Wash 
with  hot  water.  Fuse  a  por 
tion  on  Pt  foil  with  small 
quantity  of  K2  C  O3  and 
K  N  O3.  Deep  green  indi- 
.ates  Mn.— Dissolve  a  second 
portion  in  d  lute  H  Cl 
add  K4Fe(CN)e  Prus 
sian  blue  indicates  iron. — 
Dissolve  residue  in  hot  ace- 
t  c  acid  and  add  Pb2C2H3O2 
Chrome  yellow  »ppt.  indi- 
jates  Cr. 


Filtrate  .....  Al,   Zn.      Add 
(H4N)2S  in  s  tehfc  excess.  Filter. 


,p 

upon 
charcoal     add 
" 


Ppt...../.n      Filtrate..  Al. 
Add  H  Cl  to  acid 
reaction,  boil,  fil- 
_          ter,  and  add  di- 
of  Co  C12  iu)e  H4N  H  O  to 
^ca  l  (alkaline  reaction 
Pree»  a  fine  (floculent 

'"_• lif  large  amt  is 

present)   precipitate  shows  Al. 
Confirm  as  with  Zn  . . .  blue  mass. 


IV.    Evaporate  filtrate  from  Third  Group  to  dryness,  dissolve,  add  few  drops  of 
H  Cl,  boil,  filter,  and  to  filtrate  add  H4N  Cl,  H4N  HO  to  alkaline  reaction,  and  then 


Precipitate  . . .  Ba,  S ••,  Ca.     Dissoh  e  carbonates  in  dilute        Filtrate . .  soiuj'e  car- 
(20%)  acetic  acid,  add  K2Cr2O7 Filter,     bonates  of  Fifth  Group. 


Ppt 

yello'-c. 


Ba  Cr04. 
Moisten 


with  H  Cl  and  apply 
Jlame  test  Ex  p.  1*25. 


Filtrate ...  Sr,  Ca.    Add  (H4N>_>C  Os,  filter.     D  ssoKe  precipi- 
tate in  H  Cl,  add  dilute  HaS  O4  and  set  aside  for  an  hour  Filter. 


Ppt.  Sr  S  O4|  Filtrate Ca.     Add  H  .>  H  O  to  alkaline  reac- 

moisten    with  tion  and  <H4N)2C?O4.      Moisten  wnae  ppt.  with 

H  "Jl  and  apply  flame  te.st  EXP.  1-26.JH  Cl  nnd  apply  flame  test.  Dull  red  indicates  Ca. 

V.    To  nitrate  trom  Fourth  Group  concentrated  by  evaporation  add  H4N  H  O  to 
alkaline  reaction  and  then  H  Xa2  P  O4     .  let  stand  for  ten  minutes  (till  cold). 


,     *.Uvi»,~ i,»,  „.  v....v*  *~.4^/.      Concentrate  by  boiling.      Apply 

cryst alline.\  a  lim  test       Yellow  indicates  Na,  purplish  K.      If  both  are  present 


Precipitate     ,     Fiitrate Na>  K  (and  HlN). 

r  yg  ta  I  line.  |  flj  ,m  tegt      Yellow  indicates  Na,  . 

L-  u  -.V4  tne  yellow  obscures  entirelv  the  purplish  color.  Look  through  blue 
white  shows  Mg  glass  at  flame)  the  Na  color  is  not  seen  and  the  K  color  appears  red- 
dish-violet. Either  metal  may  thus  be  detected  in  the  presence  of  the  other. 

Tests  for  H4N  compounds  of  course  must  be  applied  to  the  original  solution.  Heat 
a  portion  of  this  with  Na  H  O.  H3N  is  recognized  by  (1)  odor,  (2)  turns  motet  litmus 
paper,  suspended  in  mouth  of  (but  not  touching)  test-tube,  blue,  and  (3;  b}-  fumes  with 
glass  rod  dipped  in  dilute  H  Cl. 


Pt  wire  for  flame  tests  must  be  ckan,  indeed,  all  utensils  should  be. — 
To  digest  is  to  warm  without  scalding.  C.  P.  stands  for  chemically  pure, 
and  C.  P.  acids,  etc.,  must  be  used  in  analytical  work.— Groups  iv  and 
v  are  best  tested  with  the  spectroscope  (which  see). — Js"a2C  03  may  be 
used  for  K2C  03. 


Fig.  50.— Reagent   Bottle. 

Glass  tii be  should  he 
nearly  closed  at  top  by 
fusion. 


Fig.  51. 


Tube  b  should  be  slightly  drawn  at  bottom  and  arranged  so  as  to  throw  its  stream 
straight  down  the  tube  a.  Chamber  ft  need  not  be  drawn  out  as  in  cut,  but  may  be 
closed  by  rubber  cork. 

ADVER.'TISEIMENXS. 


113 

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